# Gas in Diesel Engines
**URL:** https://boards.straightdope.com/t/gas-in-diesel-engines/265341
**Category:** Cecil's Columns/Staff Reports
**Created:** [September 21, 2004, 4:23pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341 "2004-09-21T16:23:20Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [September 21, 2004, 4:23pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/1 "2004-09-21T16:23:20Z")
Looks like I’m the first one here.
Una, in your excellent report [http://www.straightdope.com/mailbag/mdieselvsgas.html](http://www.straightdope.com/mailbag/mdieselvsgas.html) on not using Gasoline in Diesel engines, and vice versa, I wish you had commented on multifuel engines.
Particularly the older tractors that were able to switch between gasoline and kerosine. They started and warmed up on gas then a valve switched the fuel feed to the kerosine tank. Kerosine and gas are not that much alike are they. Isn’t kerosine closer to, but not the same as, diesel fuel?
How did they do it?
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### Author:  [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)
#### Post date: [September 21, 2004, 5:08pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/2 "2004-09-21T17:08:51Z")
Hi GaryM, and thank you for the compliment. Typically I tend to write very lengthy articles for other print and online publications, but I have to trim things down and stay more on-topic for Staff Reports for the Reader.
My understanding with those tractors was that multi-fuel tractors primarily used gasoline as a warm-up fuel (in the same way that a coal power plant uses natural gas or oil as a warm-up fuel), then switched to kerosene when the engine temperature was high enough. This was due in part to kerosene being more difficult to burn than gasoline due to its higher boiling point and lower volatility. It’s certainly possible, but I’m unaware of a true dual-fuel tractor that used both kerosene and gasoline equally well, since the octane rating of kerosene is such that you’d need some pretty low compression, which would hurt efficiency, power, and fuel economy.
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### Author:  [@Sean\_Factotum](https://boards.straightdope.com/u/Sean_Factotum)
#### Post date: [September 21, 2004, 6:03pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/3 "2004-09-21T18:03:53Z")
Una. I also loved your report. I wish my wife could have read it several years ago when she put diesel into our Jetta. The bill was $475, and took 5 days of work.
And she was never about to explain how she got the diesel nozzle into the gas-sized opening.
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### Author:  [@ffhard](https://boards.straightdope.com/u/ffhard)
#### Post date: [September 21, 2004, 6:49pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/4 "2004-09-21T18:49:16Z")
As a garage owner (in the UK) I see this all to often. The present record is one petrol car filled with diesel and one diesel car filled with petrol (Um, petrol means gas OK?) in the same morning!
Regarding the effect of this it all depends on how much of the wrong fuel is in the tank compared to the amount of correct fuel. For instance Volvo say that in Winter (and they are talking Swedish winter mind!) that you can add up to 25% of petrol to diesel to stop it waxing and partially solidifying. This seems extreme to me and they do admit that there will be a loss of performance, but compared to not running at all I suppose that is an option worth taking.
I have only once known a diesel injection pump fail due to wrong fuelling. In that case the car had done some 200 miles on a basically 50/50 mix of petrol and diesel, coughing and spluttering all the way. Most people would suspect something was wrong and take action sooner. All I have ever had to do is drain the tank as far as conveniently possible, change the fuel filter and then fill to the brim with the correct fuel. So far this approach has worked every time, and even with the exchange rate as it is I can’t make that come to $500, or even close.
Hmmm, maybe I should increase my prices?
On the other hand, try not to do it.
Peter
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### Author:  [@IshyGT](https://boards.straightdope.com/u/IshyGT)
#### Post date: [September 21, 2004, 7:18pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/5 "2004-09-21T19:18:08Z")
Hello Una-
Great article!! Isn’t it also true that the filling hole for a gasoline car and a diesel car are different sizes to prevent this from happening in the first place? The theory being you shouldn’t be able to put diesel in your gas car because the nozzle won’t fit!
Ishy
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### Author:  [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)
#### Post date: [September 21, 2004, 8:48pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/6 "2004-09-21T20:48:09Z")
**Sean** - looks like the $500 estimate that I got was not too bad for the US. However, maybe **ffhard** has a more correct value for other countires with respect to the labour. Your experience is quite interesting, **ffhard** , and I’m amazed that Volvo would recommend that, but then, their Winters are incredibly harsh. Being able to run at all on that much gasoline in the diesel (25-50%) seems very strange - I don’t doubt your experience, far from it, it’s just very interesting.
**IshyGT** - the nozzle should not normally fit on most cars made, but people have the damnest way of “making” things fit. One person I know who did this just assumed that the nozzle was “defective”, and held it up above the filler neck, dribbling the fuel into the neck a few ounces at a time…it must have taken her an hour to fill it up. :eek: In addition, I know of a person who filled up from a large fuel tank on their farm, which had a gasoline-sized nozzle since it was used to store gasoline 99% of the time. It’s that old 1% that gets you, however…and, it has been reported anecdotally that sometimes a station does have the wrong-size nozzle on a pump. Given the large number of gas stations and human error, I can buy this happening at least once in a while.
Thank you all for the comments, BTW.
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### Author:  [@Kansas\_Beekeeper](https://boards.straightdope.com/u/Kansas_Beekeeper)
#### Post date: [September 21, 2004, 11:50pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/7 "2004-09-21T23:50:32Z")
Having owned an older multifuel John Deere tracto,r my understanding is that they were low compression engines. You started on gas, and switched to distillate (something close to kerosene). The distillate had more BTUs than gas, and was cheaper, but was still lighter than #1 diesel. Some of the old tractors were made in two models, one low compression model for multifuel, and a higher compression for gasoline.
I never did any real work with my old JD, so I don’t really know, but all the old-timers told me that they got better fuel efficiency with distillate.
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### Author:  [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)
#### Post date: [September 22, 2004, 2:39am UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/8 "2004-09-22T02:39:09Z")
Two comments:
I believe our winters here are every bit as harsh as those in Sweden. I’ve never heard of adding gas to diesel to avoid it gelling. This is not to say I’m unaware of diesel’s propensity to gel at -40. Between growing up on a farm and driving a diesel Rabbit for several years, I know about that. But in winter one simply gets “winter diesel” which is formulated differently and doesn’t gel. At least, not down to -46C, in my personal experience. However, I couldn’t tell you whether winter diesel is chemically similar to a 4:1 diesel:gas mix. I can tell you that performance and mileage both suffer a bit, though.
Second, my dad is one of those who’ll add a bit of diesel to a gas engine to lubricate valves - not as a regular thing, but I distinctly recall an old self-propelled swather pouring out black smoke. It had, as I recall, a Wisconsin V-4 that had corroded somewhat after being parked for a few years outdoors. At least one valve was extremely sticky, and it did eventually loosen up on the diesel mix. Of course, that’s merely anecdotal. I have no idea if it would have loosened up anyways.
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### Author:  [@Meeko](https://boards.straightdope.com/u/Meeko)
#### Post date: [September 22, 2004, 5:09am UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/9 "2004-09-22T05:09:03Z")
What about adding like French Fry Grease to A Diesel engine, so called grease cars… can you do that??
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### Author:  [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)
#### Post date: [September 22, 2004, 5:14am UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/10 "2004-09-22T05:14:28Z")
> [@](#):
>
> it has been reported anecdotally that sometimes a station does have the wrong-size nozzle on a pump
Yes.
A few years ago, at the Hucks over on 22nd Street and Prairie [William? Main? The Hucks over on 22nd Street across from where the Hardee’s used to be, that they had all the trouble with the teenagers cruising…]
Anyway.
The Better Half was filling up the car with gas one day at _that_ Hucks, and he noticed that this one gas pump was off by itself, and there was nobody at it, whereas there was a line at the other pumps. So feeling very clever, he drove over there, filled up the tank, all very routine–and when he started it up, it went about 50 feet before it quit on him. Just died mysteriously. “Damn.”
So, concerned, he called for a tow, had it sent to our favorite honest auto mechanics, and they called me later in the day to report what was wrong with it: “…[embarassed pause]…well, the tank was filled with diesel fuel, so we pumped it out, and…”
I don’t remember how much it cost altogether, but “expensive” sounds about right.
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### Author:  [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)
#### Post date: [September 22, 2004, 12:08pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/11 "2004-09-22T12:08:04Z")
> [@ffhard](#):
>
> (Um, petrol means gas OK?)
I have a question. Is petrol (petroleum) exactly the same as gas (gasoline)? Or are there some slight differences?
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### Author:  [@li\_l\_Dickie\_Dirtz](https://boards.straightdope.com/u/li_l_Dickie_Dirtz)
#### Post date: [September 22, 2004, 1:24pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/12 "2004-09-22T13:24:08Z")
> [@Meeko](#):
>
> What about adding like French Fry Grease to A Diesel engine, so called grease cars… can you do that??
Sure.
[www.greasel.com](http://www.greasel.com)
> **[BIODIESEL.ORG - Home](https://www.biodiesel.org)**
>
> Biodiesel is America’s first Advanced Biofuel. It is a renewable, clean-burning diesel replacement that is reducing U.S. dependence on imported diesel, creating green jobs and improving our environment. It is made from an increasingly diverse mix of...
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### Author:  [@Zog\_10](https://boards.straightdope.com/u/Zog_10)
#### Post date: [September 22, 2004, 2:21pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/13 "2004-09-22T14:21:36Z")
> [@Una Persson](#):
>
> **Sean** - looks like the $500 estimate that I got was not too bad for the US. However, maybe **ffhard** has a more correct value for other countires with respect to the labour.
**Una** - for the sake of argument, I recently had my car drained and cleaned and the fuel filter replaced due to _contaminated_ gas and it cost me $740. Of course, I drive a Jaguar, so that probably didn’t help. :rolleyes:
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### Author:  [@AskNott](https://boards.straightdope.com/u/AskNott)
#### Post date: [September 22, 2004, 2:49pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/14 "2004-09-22T14:49:37Z")
A few years ago, I worked with a guy who had an Oldsmobile with a diesel engine. (This was during GM’s ill-fated flirtation with diesel cars, which is another story.) He had trouble with his **fuel gelling** during extreme cold. He found out that professional truck drivers **mix alcohol with diesel fuel** to prevent gelling. He bought the stuff at a truck stop, and found the mix ratio from a truck driver. After that, he had no thick-fuel problems.
Don’t get riled, you MADD mothers; I’m talking about alcohol in the car’s tank, not the driver’s. :rolleyes:
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### Author:  [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)
#### Post date: [September 22, 2004, 3:43pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/15 "2004-09-22T15:43:18Z")
> [@GuanoLad](#):
>
> I have a question. Is petrol (petroleum) exactly the same as gas (gasoline)? Or are there some slight differences?
“Petrol” is a British (and possibly other nations) term which often is a shorthand for “gasoline”. “Petroleum” however means most correctly the base oil from which gasoline is made (essentially, it means “rock oil” in the old tongue).
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [September 22, 2004, 6:37pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/16 "2004-09-22T18:37:23Z")
All very interesting posts, particularly about the teenagers at Hardee’s.
Fans of The Amazing Race may remember in one of the earlier races where several of the teams filled the fuel tanks on their cars with gasoline. This despite the sticker on the inside of the filler door that said “Diesel Fuel Only” and in English too. They had to be towed and have the systems drained etc. So at least in North Africa, the gasoline nozzle fits into the diesel filler neck.
I add Power Service additive to the diesel fuel I put into my tractor. Prevents gelling and raises the cetane numbers.
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### Author:  [@friendscallmelenny](https://boards.straightdope.com/u/friendscallmelenny)
#### Post date: [September 22, 2004, 10:46pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/17 "2004-09-22T22:46:56Z")
As a point of clarification. Diesel nozzles are usually larger in diameter BUT not always, so it could be easy to put diesel in a gas car at some stations. It is usually not a problem to put gas in a diesel, as I have proven before. Twice I have filled my GMC truck with gas by mistake (both times I mistook a green handle for a diesel pump) but I should know better.
Both times I headed back on the highway and then sputtered to a stop several miles down the road. Luckily, I have two tanks and both times I was able to switch tanks and restart the vehicle after draining the fuel filter. Later I siphoned as much gas as possible out of the tank and refilled it.
My truck has not suffered ill effects despite my stupidity.
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### Author:  [@Walton\_Firm](https://boards.straightdope.com/u/Walton_Firm)
#### Post date: [September 23, 2004, 6:17pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/18 "2004-09-23T18:17:17Z")
The instruction manual for my first car, a Peugeot 306, also advised mixing some unleaded gasoline with the diesel during cold winters. There was a table giving the proportions to use for different temperature ranges. I seem to remember that the table went all the way up to 20 or 25%, for temperatures of below minus 30 centigrade or so.
If I remember correctly, the manual also said something to the effect that gas stations will normally already supply a different diesel mixture in winter than in summer, so normally you don’t need to do anything special, unless either the temperature suddenly drops very sharply, or you find yourself stranded in the snow with only a can of “summer diesel” for whatever reason.
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### Author:  [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)
#### Post date: [September 23, 2004, 10:37pm UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/19 "2004-09-23T22:37:14Z")
see [http://members.iinet.net.au/~mbuckler/fuel/index.shtml](http://members.iinet.net.au/~mbuckler/fuel/index.shtml)
for the names of various fuels in different countries.
It’s illegal here to run your vehicle on any fuel which has not been taxed, including cooking oil.
A small amount of diesel in an Otto [four-stroke] engine will not be a disaster if you dilute it with petrol as much as possible and as quickly as you can. Your tailpipe will smoke like hell, though, until it has all worked its way through.
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### Author:  [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)
#### Post date: [September 24, 2004, 3:46am UTC](https://boards.straightdope.com/t/gas-in-diesel-engines/265341/20 "2004-09-24T03:46:38Z")
> [@GuanoLad](#):
>
> I have a question. Is petrol (petroleum) exactly the same as gas (gasoline)? Or are there some slight differences?
A main difference is that Australian petrol is SHIT. Our “premium” is the same as the cheapest, lowest octane stuff you can get in Europe and the UK. Not sure about the States, mind you.
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