# Adding diesel fuel to gasohol to increase mileage/efficiency? **URL:** \ **Category:** Factual Questions\ **Created:** [January 7, 2010, 7:32pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055 "2010-01-07T19:32:06Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 10, 2010, 2:39pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/41 "2010-01-10T14:39:16Z")
Hey Rick. There’s a late Christmas present for you in the pit. Sorry I couldnt get you something better. ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [January 10, 2010, 5:18pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/42 "2010-01-10T17:18:04Z")
> [@The\_Central\_Scrutinizer](#): > > Look, I’m not asking your permission or approval, just some information. If you don’t approve, go have a beer (“whine”?) instead & don’t respond. Oh, BTW, you didn’t mention the wheel-spinning, door-slamming, overloading, donuts-in-the-parking-lot crowd. Do you think there’s any benefit to be found there, or that they’re any more righteous? Find a shorter horse. The fact that others abuse rental cars does not excuse your potential abuse. This falls under the ancient Babylonian principle of “just because Nur Ab Sal beats his donkey doesn’t mean I should give my donkey water of the tainted well.” And the rental car isn’t “YOURS” when you rent it. Phone the rental car company and ask them for a copy of their contract T&Cs; all answers can be found in there. And your excuse of “national security” and “doing it for the children” is so ludicrous it cannot be addressed in this forum. What you can be criticized for in this forum is lack of a scientific method in your madness. Ignoring the lack of ethics of risking damaging a rental car, your experiment suffers from the following problems: 1. You will be working with a sample size of one. 2. You did not say you would be doing emissions testing of the vehicle to determine the effects mixing the diesel would have on NOx, CO, HC, PM10/PM2.5, and other emissions. I can assure you that the EPA will really want to know this… 3. You have no way of assessing long-term impacts to the fuel system, fuel pump, fuel injectors, valves, pistons, oil life, catalyst, and other items. You have no control for measuring differences in sludge buildup or corrosion throughout the system. 4. You have no way to determine the multi-use capability of the mixture unless you are planning to test the vehicle at these different fuel mixtures under a variety of different loads, ambient conditions (temperature and humidity), traffic conditions, and engine demand. Are you going to be doing dyno testing? How will you judge power or torque differences? “Seat of the pants” analysis by shade-tree mechanics has been proven to be outrageously unreliable (a/k/a “I put a new K&N filter on, and I ust be getting 10 more hp!”) 5. You have not said that you are even going to do a basic ASTM ultimate analysis on the gasoline and diesel, let alone an HHV/LHV measurement, analysis of trace elements, etc. You might justify your lack of scientific method by saying “I’ll buy from the same gas station every time”, but do you even know the relative error in fuel quality from a single station? 6. What’s your technical and scientific background for even being able to properly set up the experiments and analyze the results? I have a graduate Engineering degree, am a licensed Professional Engineer, have studied IC engine combustion in grad school, and worked in the fuels in combustion area professionally for about 2 decades, and I don’t think I could really set up an experiment that would be good enough to run as an ASME peer-reviewed paper without a huge amount of effort. So here we have the summary: 1. Your interest in trying to improve gas mileage is admirable. 2. But you have no good scientific method for even your sample size of 1. 3. Your sample size of one, even if scientifically done, is not extensible without some error to the population as a whole. 4. Given (2) and (3), and the ethical challenge of performing experiments without permission on another’s equipment, this points to a case where some may judge your proposed course of action is unwise. 5. I suggest you start with a trip to your local university which has an Engineering school or good technical library, and do a literature review to see how diesel/gasoline mixtures have been tested in the past by others, and what their results were. ---
**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\ **Post date:** [January 10, 2010, 5:28pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/43 "2010-01-10T17:28:09Z")
> [@The\_Central\_Scrutinizer](#): > > Actually, while I’m renting it, it IS mine. Heh, that’s funny. Yeah, no it’s not. Title has in no way been conveyed to you. :rolleyes: ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 10, 2010, 6:26pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/44 "2010-01-10T18:26:23Z")
I bet that if you put diesel in a rental car, even a little, and you mess it up, even a little, the company will likely catch you. I am sure once in great while but often enough somebody accidentally puts diesel in regular car. They probably have a company directive that says something to the effect of “if there are sudden fuel/emmisions/whatever problems, take a sample of fuel to see if someone’s done it yet again”. Unless you go all CSI crime scene on cleaning on the rental car’s tank and fuel system, they are going to find diesel in there. And if they think they have a chance of making YOU pay for it, they are going to try. I know some folks that damaged a rental car. It was more bad luck that wanton disregard for other peoples property. They still got dinged for a big and expensive repair job. Fortunately, it was split among six people that had some disposable income that the rental car company was quite happy to help them dispose of. ---
**Author:** ![TurboNuke](https://avatars.discourse-cdn.com/v4/letter/t/f19dbf/32.png) [@TurboNuke](https://boards.straightdope.com/u/TurboNuke)\ **Post date:** [January 10, 2010, 6:55pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/45 "2010-01-10T18:55:41Z")
> [@The\_Central\_Scrutinizer](#): > > (“Doh!”) Read the thread. I have read the thread. It seems the purpose is to ruin a rental car and avoid being responsible for it. Are you trying to save money or get better gas mileage. Do you have a very large supply of diesel fuel that you got for free? Because honestly, there is no reason to do what you are doing. Ok I now see where you are are saying you want higher gas mileage. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [January 10, 2010, 9:40pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/46 "2010-01-10T21:40:21Z")
Quote: Considering that the 2 main ideas behind “gasohol” (E10 & E85) have been to 1. Decrease our dependence on foreign oil & 2. Decrease tailpipe emissions, 2 other negative effects have certainly been noted (by me, at least!). 1. The net cost has gone up, both at the pump & in reduced mileage/efficiency & 2. While the internal combustion has gotten more efficient, the resultant elemental carbon has been left to accumulate inside the engine, notably in critical & expensive areas, requiring either regular additions of chemical treatments on up to costly mechanical services to remove. Wrong: the main idea behind gasohol is to funnel money to big farmers who produce corn. Ethyl alcohol has only 67% of the energy content of gasoline, and producing alcohol results in more energy expended than is returned. It is a complete farce and goes on because the senators from the corn-growing Midwest states want the subsidy. We could buy alcohol (from Brazil) cheaper than we can produce it-but the farm lobby put in a tariff to prevent that! :smack: ---
**Author:** ![Bobalude](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@Bobalude](https://boards.straightdope.com/u/Bobalude)\ **Post date:** [January 10, 2010, 9:57pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/47 "2010-01-10T21:57:41Z")
> [@The\_Central\_Scrutinizer](#): > > 1. Using quality tires (we like the Goodyear TripleTread Assurance) & Pump them to their rated maximum for improved mileage, handling, even tread wear, cooler operating temperature, longer life &, of course, better mileage. I would caution against inflating to the maximum rated amount. You may encounter excessive tire wear in the center of the tire: [Sample Picture](http://www.procarcare.com/images/shar/encyclopedia/8852oc1.gif) Also risk of reduced handling/control/braking characteristics. Over inflation reduces the contact patch of the tire. One overworn set of tires or one accident can easily wipe out savings from gas efficiency… and some. Not to mention risk of bodily harm. Should inflate the tires to the auto manufacturer’s recommended levels if you are using the OEM tire size. ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [January 10, 2010, 10:02pm UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/48 "2010-01-10T22:02:22Z")
> [@Johnny\_L.A](#): > > That’s what I was going to say. Mis-fueling is an issue to watch for in aircraft. Put jet fuel in a piston engine, and you lose power. Put avgas into a jet engine, and you risk burning it up. A more subtle and insidious problem is that while many aircraft engines are certified to run on ordinary car gasoline (Mogas), any ethanol in the gasoline can cause dangerous problems (damage to rubber parts, vapour lock causing loss of power, etc.) It is very difficult (at least here) to get a guarantee from a fuel supplier that there is no ethanol admixed in the gasoline. It is also very difficult to detect ethanol in quantities of 5% or less (test kits are available, but the standard test of adding water and checking for a drop in volume is unreliable). Effectively pilots are forced to use Avgas, which is much more expensive. ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 2:51am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/49 "2010-01-11T02:51:29Z")
> [@Una\_Persson](#): > > The fact that others abuse rental cars does not excuse your potential abuse. This falls under the ancient Babylonian principle of “just because Nur Ab Sal beats his donkey doesn’t mean I should give my donkey water of the tainted well.” > > And the rental car isn’t “YOURS” when you rent it. Phone the rental car company and ask them for a copy of their contract T&Cs; all answers can be found in there. And your excuse of “national security” and “doing it for the children” is so ludicrous it cannot be addressed in this forum. > > Why not? It’s regularly used by the Establishment all the time; no one seems to complain about much more egregious offenses using the same logic. > > What you can be criticized for in this forum is lack of a scientific method in your madness. Ignoring the lack of ethics of risking damaging a rental car, your experiment suffers from the following problems: > > Well, as I mentioned previously, I didn’t visit to ask approval or permission; if you were the scientist that you seem to represent, the interest in the pursuit of knowledge would exceed the personal bias against the methods involved in searching for the Answer, regardless of your feelings to the contrary. > > 1. You will be working with a sample size of one. > > That’s correct, just 1. Unless someone would like to increase the sample rate, or I could do it a bit more scientifically, & record the performance data on a number of different vehicles, although I personally would be limited (until I get myself cloned) to 1 at a time… I’ve spent more time w/ my hands on metal than books; perhaps you’d like to add your expertise in other areas? > > 1. You did not say you would be doing emissions testing of the vehicle to determine the effects mixing the diesel would have on NOx, CO, HC, PM10/PM2.5, and other emissions. I can assure you that the EPA will really want to know this… > > & I’d be happy to let them know about it, as soon as I had enough data. I give the Establishment all the respect it’s due, even if it’s none. Perhaps if they’d have an interest in furthering the concept of flexible-fueled vehicles, it’d be a lot more feasible to make our own fuel, but as I pointed out earlier, not only would we be required to purchase our own equipment, the modifications necessary to our vehicles, the materials needed to feed the process, we’d also have to pay yet another agency for “permission” to do it. But since we’d hardly get any write-off for the expenditures, I’d consider it fair to ignore asking “permission” & keeping what we’d otherwise be paying in taxes & fees as fair compensation. Isn’t that what the Amish do, in a more roundabout way? Since we’re not required to have social “insecurity” numbers, & they choose not to participate in the System, their means of transport is hay-powered _&_ self-replicating to boot! But, I wonder just when the EPA will get around to sticking some emissions device up their horses’ asses… methane emissions, you know; it’s a greenhouse gas, too… > > 1. You have no way of assessing long-term impacts to the fuel system, fuel pump, fuel injectors, valves, pistons, oil life, catalyst, and other items. You have no control for measuring differences in sludge buildup or corrosion throughout the system. > > So, has the EPA, etc. also done these assessments on alcohol-laced fuel? If so, they seem satisfied with us being forced to buy fuel which sacrifices both our investments (admittedly poor at best) & our finances in additional maintenance costs. Not to mention the increased operating costs. > > 1. You have no way to determine the multi-use capability of the mixture unless you are planning to test the vehicle at these different fuel mixtures under a variety of different loads, ambient conditions (temperature and humidity), traffic conditions, and engine demand. Are you going to be doing dyno testing? How will you judge power or torque differences? “Seat of the pants” analysis by shade-tree mechanics has been proven to be outrageously unreliable (a/k/a “I put a new K&N filter on, and I ust be getting 10 more hp!”) > > I’ve nowhere suggested that whatever I find as an advantageous % would be the same for every other type of vehicle. However, since I’ve never heard of anyone else asking those Questions, & I spent 18 hours STR8 online yesterday searching, perhaps you’d find it an interesting topic to advise upon? You sound eminently qualified! > > 1. You have not said that you are even going to do a basic ASTM ultimate analysis on the gasoline and diesel, let alone an HHV/LHV measurement, analysis of trace elements, etc. You might justify your lack of scientific method by saying “I’ll buy from the same gas station every time”, but do you even know the relative error in fuel quality from a single station? > > Yes, I know of the variability of fuel sources; it varies all the time according to the bidding from suppliers on the market, the season, the location, even the politics, as I read on another post, etc. Yet somehow this hasn’t seemed to bother anybody about whatever is passed off as “safe” & taxed. > > 1. What’s your technical and scientific background for even being able to properly set up the experiments and analyze the results? I have a graduate Engineering degree, am a licensed Professional Engineer, have studied IC engine combustion in grad school, and worked in the fuels in combustion area professionally for about 2 decades, and I don’t think I could really set up an experiment that would be good enough to run as an ASME peer-reviewed paper without a huge amount of effort. > > So, any thoughts on your adding your obvious expertise to the effort? It does take more effort than merely raising objections & criticizing… > > So here we have the summary: > > 1. Your interest in trying to improve gas mileage is admirable. > > Thank you. I see it as my Patriotic Duty as a matter of National Security & I’m doing it For The Children. There, I’ve said the Majick Words. > > 1. But you have no good scientific method for even your sample size of 1. > > As I mentioned before, that doesn’t necessarily have to remain so. > > 1. Your sample size of one, even if scientifically done, is not extensible without some error to the population as a whole. > > Perhaps this issue might be worthy of pursuit on an “official” level. But until there’s a benefit to those in power, I doubt it will be. Take this an open invite to broaden the base of information! > > 1. Given (2) and (3), and the ethical challenge of performing experiments without permission on another’s equipment, this points to a case where some may judge your proposed course of action is unwise. > > They probably said the same thing to the FDA & the Army medical corp… but that didn’t stop them either. > > 1. I suggest you start with a trip to your local university which has an Engineering school or good technical library, and do a literature review to see how diesel/gasoline mixtures have been tested in the past by others, and what their results were. Actually, since I’ve found absolutely no reference to any info online, I’d rather doubt that it’s available on paper in the library. Actually, I’ve been trying to maximize the informational base-searching by visiting sites like this & asking Questions. Other than a few incidental references of an anecdotal nature, a few negative but more positive, most of what I’ve encountered has hardly been informational. But, here’s your chance to shine! Your points are well-made, & I’d welcome your informational input. Otherwise, it’s merely more criticism of a more well-educated nature. I’ll keep you up-to-date on my progress. ---
**Author:** ![jasonh300](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@jasonh300](https://boards.straightdope.com/u/jasonh300)\ **Post date:** [January 11, 2010, 2:57am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/50 "2010-01-11T02:57:09Z")
> [@The\_Central\_Scrutinizer](#): > > Thank You. BTW, how was the mileage? This is the kind of positive, informative response I appreciate! Sorry…didn’t pay much attention to it. It was all city driving and we’re talking about a vehicle that probably only gets 5 MPG anyway, so even a 20% increase (or decrease) in mileage wouldn’t have been noticeable. It was a full size 26’ truck with an International gasoline engine. Probably a mid to late 80s model. When I realized what I’d done, I stopped pumping and a friend who was with me saw a trucker filling up his semi across the station. He suggested we ask the trucker if the diesel was going to be a problem. We told the trucker what had happened and he had this amused sort of look on his face and was probably thinking that regular people should be allowed to operate large trucks. The trucker told us to top it off with unleaded and it might smoke a little, but we’d probably be ok. He said it wasn’t the first time he’d seen someone do the exact same thing. I’m also remembering that we were working with $25.00 for gas, and that topping it off wasn’t an option. Thinking that this must’ve been around 1996, gas or diesel would’ve been right around $1.00 a gallon, so we probably had 5 gallons of diesel, plus 20 gallons of regular, plus whatever was still in the tank (very little). The truck didn’t run any different, or produce any visible smoke. The exhaust just smelled like diesel. ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:03am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/51 "2010-01-11T03:03:02Z")
> [@ralph124c](#): > > Quote: > Considering that the 2 main ideas behind “gasohol” (E10 & E85) have been to 1. Decrease our dependence on foreign oil & 2. Decrease tailpipe emissions, 2 other negative effects have certainly been noted (by me, at least!). 1. The net cost has gone up, both at the pump & in reduced mileage/efficiency & 2. While the internal combustion has gotten more efficient, the resultant elemental carbon has been left to accumulate inside the engine, notably in critical & expensive areas, requiring either regular additions of chemical treatments on up to costly mechanical services to remove. > > Wrong: the main idea behind gasohol is to funnel money to big farmers who produce corn. Ethyl alcohol has only 67% of the energy content of gasoline, and producing alcohol results in more energy expended than is returned. It is a complete farce and goes on because the senators from the corn-growing Midwest states want the subsidy. We could buy alcohol (from Brazil) cheaper than we can produce it-but the farm lobby put in a tariff to prevent that! :smack: Yes, you’re completely correct on the reasons “behind closed doors” for mandating gasohol. But the publicized excuse has been as I listed above. Doesn’t make it any smarter; we’re now paying more for grain products, people are still going hungry around the world, we’re lessa ble to afford the food here @ home, while the net fuel cost has risen & we’re spending more in harvesting it than we’re getting back. An excellent example of yet another gov’t boondoggle. Hence my search for alternatives… thank you for pointing out those facts! ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 11, 2010, 3:07am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/52 "2010-01-11T03:07:57Z")
> [@The\_Central\_Scrutinizer](#): > > I’ll keep you up-to-date on my progress. Let us know when you show up on Judge Judy or The People’s Court. ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:11am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/53 "2010-01-11T03:11:22Z")
> [@Turek](#): > > Heh, that’s funny. > > Yeah, no it’s not. Title has in no way been conveyed to you. :rolleyes: Gee, OK, I’ll keep that in mind. :smack: ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:16am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/54 "2010-01-11T03:16:38Z")
> [@billfish678](#): > > I bet that if you put diesel in a rental car, even a little, and you mess it up, even a little, the company will likely catch you. > > I am sure once in great while but often enough somebody accidentally puts diesel in regular car. They probably have a company directive that says something to the effect of “if there are sudden fuel/emmisions/whatever problems, take a sample of fuel to see if someone’s done it yet again”. > > Unless you go all CSI crime scene on cleaning on the rental car’s tank and fuel system, they are going to find diesel in there. And if they think they have a chance of making YOU pay for it, they are going to try. > > I know some folks that damaged a rental car. It was more bad luck that wanton disregard for other peoples property. They still got dinged for a big and expensive repair job. Fortunately, it was split among six people that had some disposable income that the rental car company was quite happy to help them dispose of. “if” count: 4 :dubious: ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [January 11, 2010, 3:17am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/55 "2010-01-11T03:17:37Z")
> [@The\_Central\_Scrutinizer](#): > > Actually, since I’ve found absolutely no reference to any info online, I’d rather doubt that it’s available on paper in the library. Actually, I’ve been trying to maximize the informational base-searching by visiting sites like this & asking Questions. Other than a few incidental references of an anecdotal nature, a few negative but more positive, most of what I’ve encountered has hardly been informational. I’ll tell you what - I’ll ask my librarian to look for me tomorrow with respect to mixing gasoline and diesel, and see if I can find anything on it. It’s possible there was work done around the Second World War, as there were many efforts to try and mix all sorts of fuels back then. ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:31am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/56 "2010-01-11T03:31:18Z")
> [@Bobalude](#): > > I would caution against inflating to the maximum rated amount. You may encounter excessive tire wear in the center of the tire: > > [Sample Picture](http://www.procarcare.com/images/shar/encyclopedia/8852oc1.gif) > > Also risk of reduced handling/control/braking characteristics. Over inflation reduces the contact patch of the tire. One overworn set of tires or one accident can easily wipe out savings from gas efficiency… and some. Not to mention risk of bodily harm. > > Should inflate the tires to the auto manufacturer’s recommended levels if you are using the OEM tire size. Yeah, that’s the standard tire-store & auto manuf. mantra. Yet I’ve never encountered it, & I’ve read much info to the contrary. The info I mentioned is correct. In all the years of driving, I’ve never had a set of tires worn in the middle before they were worn along the outside edge, & once I increased the pressure to the rated maximum, all was as I’d said. Roughly 1/3-1/2 way through the tires life, I have them dismounted, switched so that the opposite side now faces out (the direction of rotation remaining the same) & get more than the rated mileage life out of the tire. This is only applicable for symmetrical tread designs. I also spray marine-grade silicone inside & out to minimize ozone damage & help seal the tires micropores from seeping pressure gradually over the months. That saves fuel as well as tires. The posted tire pressure maximum on a car’s tires is just that, the maximum; on a truck, it’s just the opposite; the posted pressure is the minimum for the rated load. This is to ensure that the tires don’t overheat, which aside from making a really tough fire to put out (ever seen a tire fire get out of control?), wastes fuel in the generation of the heat. Not the mention the difficulty of handling a flat on the front wheel of a rig while in motion… :eek: ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 11, 2010, 3:33am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/57 "2010-01-11T03:33:41Z")
> [@The\_Central\_Scrutinizer](#): > > “if” count: 4 :dubious: You dont even understand the concept of “if” apparently. The first “if” is YOU putting diesel in the car. According to you that is a given, if not a moral imperative. The second “if” is the car showing problems. YOU said you would drive the rental until problems showed up. So, thats another given. And you do realize that car computers can RECORD stuff don’t you. Those records will show that wierd shit started happening AFTER you rented the car. You are just hoping the problems actually go away before you return the car. The third “if” is the rental company wondering “if” somebody accidentally put some strange fuel in and decides to test. Well, that one fails, because, instead, somebody like YOU purposes put the wrong shit in. The fact that they had the “if” for accidental mixed up with the “if” for unallowed experimentation is irrelevant. The final “if” is the “if” they think they can get money from you for messing up their rental car. Okay, you got me on that one. PLEASE O PLEASE actually do this experiment and let us know how it goes. Oh, and hi OPAL. ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:35am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/58 "2010-01-11T03:35:48Z")
> [@hibernicus](#): > > A more subtle and insidious problem is that while many aircraft engines are certified to run on ordinary car gasoline (Mogas), any ethanol in the gasoline can cause dangerous problems (damage to rubber parts, vapour lock causing loss of power, etc.) > > It is very difficult (at least here) to get a guarantee from a fuel supplier that there is no ethanol admixed in the gasoline. It is also very difficult to detect ethanol in quantities of 5% or less (test kits are available, but the standard test of adding water and checking for a drop in volume is unreliable). > > Effectively pilots are forced to use Avgas, which is much more expensive. Yeah, what he said… 😃 ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 3:58am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/59 "2010-01-11T03:58:44Z")
> [@billfish678](#): > > You dont even understand the concept of “if” apparently. > > The first “if” is YOU putting diesel in the car. According to you that is a given, if not a moral imperative. > > Yes, I feel morally bound to preserve Homeland Security & our Children; it’s my Patriotic Doody. 😃 > > The second “if” is the car showing problems. YOU said you would drive the rental until problems showed up. So, thats another given. And you do realize that car computers can RECORD stuff don’t you. Those records will show that wierd shit started happening AFTER you rented the car. You are just hoping the problems actually go away before you return the car. > > Hence the gradual addition of diesel, & the return to a pre-problem state if any show up. Oops, there’s that word again… even “if” no problems showed up, there’s a point that using diesel will provide diminishing returns, due to the design limitation of a spark-ignited engine & the somewhat higher cost of road diesel. However, there’s always the option of using off-road diesel… (as in, home heating fuel, essentially untaxed #2). OMG! A conspiracy! :eek: > > The third “if” is the rental company wondering “if” somebody accidentally put some strange fuel in and decides to test. Well, that one fails, because, instead, somebody like YOU purposes put the wrong shit in. The fact that they had the “if” for accidental mixed up with the “if” for unallowed experimentation is irrelevant. > > Yes… it’s a real damn shame, huh? ☹ > > The final “if” is the “if” they think they can get money from you for messing up their rental car. Okay, you got me on that one. PLEASE O PLEASE actually do this experiment and let us know how it goes. > > Yes, I will indeed. I’ve appreciated crossing wits with all those who’ve decided to merely criticize rather than be informative, but in addition to actually finding a few occasional gems of info, I’ve had a wonderful time doing it! 😛 > > Oh, and hi OPAL. Heeyy! Wazzup, Duuude? 🆒 ---
**Author:** ![The\_Central\_Scrutinizer](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@The\_Central\_Scrutinizer](https://boards.straightdope.com/u/The_Central_Scrutinizer)\ **Post date:** [January 11, 2010, 4:02am UTC](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055/60 "2010-01-11T04:02:41Z")
> [@Una\_Persson](#): > > I’ll tell you what - I’ll ask my librarian to look for me tomorrow with respect to mixing gasoline and diesel, and see if I can find anything on it. It’s possible there was work done around the Second World War, as there were many efforts to try and mix all sorts of fuels back then. OK, it’s a deal: I Promise Not To Blow Anything Up Until I Hear Back From You. & I appreciate your offer to ask. I’ve got 2 jobs, my time’s sorta crunched. Gotta go, be up @ 4:30Am tomorrow… 🙂 [Previous page](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055.md?page=2) [Next page](https://boards.straightdope.com/t/adding-diesel-fuel-to-gasohol-to-increase-mileage-efficiency/524055.md?page=4)