# Question about deisel fuel... **URL:** \ **Category:** Factual Questions\ **Created:** [March 25, 2003, 12:23pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003 "2003-03-25T12:23:57Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![newcrasher](https://avatars.discourse-cdn.com/v4/letter/n/b3f665/32.png) [@newcrasher](https://boards.straightdope.com/u/newcrasher)\ **Post date:** [March 25, 2003, 12:23pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/1 "2003-03-25T12:23:57Z")
I was filling up mu F250 V-8 Turbo Powerstroke pickup yesterday when I looked down at the gas nozzle and my heart skipped a beat. For a second I thought I was putting regular gas in it. Luckily it WAS deisel. What would happen if I put regular unleaded in it? If I notinced after a few gallons could I fill it up with deisel and have the gas/deisel mixture work without fouling things too much? I have also heard you can run a mix of kerosene and gas. Anyone know? ---
**Author:** ![Pergau](https://avatars.discourse-cdn.com/v4/letter/p/7c8e57/32.png) [@Pergau](https://boards.straightdope.com/u/Pergau)\ **Post date:** [March 25, 2003, 1:30pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/2 "2003-03-25T13:30:32Z")
\*\*\* Do not try this at home \*\*\* I believe that you can run a diesel car on a mixture of petrol and diesel although it’s not good for it. But you really mess up the engine if you put diesel in a petrol engine. ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [March 25, 2003, 1:33pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/3 "2003-03-25T13:33:00Z")
I used to work at a number of dealership service areas, and one customer (with a brand new dodge pickup, a diesel) came is all pissed-off & proceeded to tear the service manager a new asshole. Said he just bought the truck & already the engine had major problems. They started taking it apart & discovered someone had filled it with gas, & destroyed the engine. Turns out his wife took it for a spin & decided to fill it up for him. The service manager told the mechanics to replace everything, & to take their time. I think the total bill was around $8000. Never take out your anger on a guy who’s going to charge you to fix your car. I don’t know if a gallon or 2 would really make a difference, but I wouldn’t bet my truck on it. I recently had to fill my car with a tank that had once had a small amount of fuel oil (diesel) in it, and I was afraid the residual amount on the walls & bottom was going to screw up my car. Thankfully, nothing happened. ---
**Author:** ![herman\_and\_bill](https://avatars.discourse-cdn.com/v4/letter/h/f1d935/32.png) [@herman\_and\_bill](https://boards.straightdope.com/u/herman_and_bill)\ **Post date:** [March 25, 2003, 1:40pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/4 "2003-03-25T13:40:15Z")
And it has to do with octane. Gasoline mixed in diesel fuel will inhibit combustion in a diesel engine and diesel fuel mixed in gasoline will ignite too soon in a gasoline engine. ---
**Author:** ![Blown\_Injected](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)\ **Post date:** [March 25, 2003, 1:53pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/5 "2003-03-25T13:53:54Z")
are you sure you don’t have that backwards herman? ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 25, 2003, 2:14pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/6 "2003-03-25T14:14:41Z")
Back when we still sold diesel cars, I had a number of diesels brought in with gas in the tanks. Some had been started, some had not. Procedure was to drain the tank, change the filter, and fill with diesel. Then we would gravity feed diesel to the pump and crank until the car started. Never had to do any other repairs. YMMV as the diesel engines of today are quite a bit different than what we had in 1990. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [March 25, 2003, 3:45pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/7 "2003-03-25T15:45:01Z")
As to your other question, yes you can get away with using kerosene in a diesel engine. Diesel fuel, kerosene, and even jet fuel are basically the same thing except for some additives and are largely interchangable. We had a couple of threads on this a few months ago. However, you might get into some serious trouble if you try this at home. Kerosene and even diesel fuel sold in bulk to farmers does not have the same taxes attached as diesel fuel does and the government gets really ticked if you try to save some cash by cheating them out of it. ---
**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\ **Post date:** [March 25, 2003, 4:26pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/8 "2003-03-25T16:26:18Z")
Hey, they did this on Amazing Race last season! Filled up diesel SUV’s with gasoline. They just died after a bit of driving, and they had to drain the whole fuel system, but the vehicles seemed okay. ---
**Author:** ![Hermann\_Cheruscan](https://avatars.discourse-cdn.com/v4/letter/h/b782af/32.png) [@Hermann\_Cheruscan](https://boards.straightdope.com/u/Hermann_Cheruscan)\ **Post date:** [March 25, 2003, 7:23pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/9 "2003-03-25T19:23:27Z")
Isn’t kerosene known as “Diesel#1”, and truck stop diesel is known as "Diesel#2? ---
**Author:** ![stevephillips](https://avatars.discourse-cdn.com/v4/letter/s/3ab097/32.png) [@stevephillips](https://boards.straightdope.com/u/stevephillips)\ **Post date:** [March 25, 2003, 7:37pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/10 "2003-03-25T19:37:52Z")
Diesel also provides lubrication for the injector pump. Too much gas would destroy it, and they cost $1,000+ ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 25, 2003, 8:56pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/11 "2003-03-25T20:56:48Z")
There is a danger to mixing diesel with gas. With gas, there is excess fumes and not enough oxygen during fill-up. With diesel, the opposite is true; not enough fumes and too much oxygen. Mixing the two fuels will create just the right conditions of oxygen and fumes that would lead to an explosion. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 25, 2003, 9:06pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/12 "2003-03-25T21:06:35Z")
cite? ---
**Author:** ![herman\_and\_bill](https://avatars.discourse-cdn.com/v4/letter/h/f1d935/32.png) [@herman\_and\_bill](https://boards.straightdope.com/u/herman_and_bill)\ **Post date:** [March 25, 2003, 11:53pm UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/13 "2003-03-25T23:53:25Z")
> [@](#): > > \*Originally posted by Blown & Injected \* > \*\*are you sure you don’t have that backwards herman? \*\* You would think so but not: The light distillates that gasolines are made from have a natural high-octane index. The middle distillates that diesel fuels come from have a high cetane index. The octane and cetane indexes are INVERSE scales. A fuel that has a high octane number has a low cetane number, and a high cetane fuel has a low octane number. Anything with a high octane rating will retard diesel fuel’s ability to ignite. That’s why each fuel has developed along with different types of engine designs and fuel delivery systems. Gasoline mixed in diesel fuel will inhibit combustion in a diesel engine and diesel fuel mixed in gasoline will ignite too soon in a gasoline engine. This is the cite this is from: [http://139.81.139.106/mixing\_gasoline\_and\_diesel.htm](http://139.81.139.106/mixing_gasoline_and_diesel.htm) ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 26, 2003, 3:08am UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/14 "2003-03-26T03:08:32Z")
> [@](#): > > \*Originally posted by Rick \* > \*\*cite? \*\* Remembered from a diesel owner’s handbook (by Mercedes Benz?) printed in the late70s/early80s. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [March 26, 2003, 4:29am UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/15 "2003-03-26T04:29:28Z")
In my experience in the end-user petroleum sales industry, you’d just need to get it drained. Some of my less-than-stellar co-workers managed to fill diesel trucks with gasoline on more than one occasion. If the truck didn’t have a 2nd tank, they had to be towed to wherever she had that done. Then, she’d come back with these huuuuuge plastic gasoline containers, and dump it back in the underground tanks. I asked about that (Hmm. Impertinent lad. But I didn’t really need that job anyhow…), and she said it was beneficial to add a bit of diesel every now and again to… I forget. Something about burning off deposits, pretty much like herman’s link but backward. Of course, she was also cheap enough to pay absolute Alberta minimum wage back when it was lower than it is even now. ---
**Author:** ![something\_clever](https://avatars.discourse-cdn.com/v4/letter/s/3bc359/32.png) [@something\_clever](https://boards.straightdope.com/u/something_clever)\ **Post date:** [March 26, 2003, 8:11am UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/16 "2003-03-26T08:11:28Z")
to go along with herman, blown, think about it this way. you dont use 87 octane on a turbocharged or supercharged car right? why? it will knock. why? because it ignites before it should because of the higher compression. the higher the octane the ‘slower’ the burn… ---
**Author:** ![Blown\_Injected](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)\ **Post date:** [April 2, 2003, 4:16am UTC](https://boards.straightdope.com/t/question-about-deisel-fuel/164003/17 "2003-04-02T04:16:33Z")
> [@](#): > > \*Originally posted by herman\_and\_bill \* > \*\*You would think so but not: > > The light distillates that gasolines are made from have a natural high-octane index. The middle distillates that diesel fuels come from have a high cetane index. The octane and cetane indexes are INVERSE scales. A fuel that has a high octane number has a low cetane number, and a high cetane fuel has a low octane number. Anything with a high octane rating will retard diesel fuel’s ability to ignite. That’s why each fuel has developed along with different types of engine designs and fuel delivery systems. Gasoline mixed in diesel fuel will inhibit combustion in a diesel engine and diesel fuel mixed in gasoline will ignite too soon in a gasoline engine. > > This is the cite this is from: [http://139.81.139.106/mixing\_gasoline\_and\_diesel.htm](http://139.81.139.106/mixing_gasoline_and_diesel.htm) \*\* Ahhhh, very interesting. I had only thought as far as gasoline is close to an explosive (especially when used to light a pile of leaves 🙂 ) and diesel is hard to light. - but then diesel is not really lit light gas is with a spark - it compresses to ignite.