running gasoline/diesel mix in an emergency

[Comodave]

If I were concerned about running out of diesel and were thinking about running gas into my diesel I would first think about carrying more diesel. Maybe a small bladder or a couple of drums and empty them into the main tanks asap after burning some of the fuel out of them. Way more reasonable thing to do than possibly, most likely, destroying my diesel engine.

 

[BandB]

I have my reasons

Well, they can't be good ones.

Only thing dumber than putting the gas in the diesel, is putting yourself in position to even consider that. I hate to even think that you are serious in asking this question.

 

[utclmjmper]

It won't "sputter to a halt",, it will SEIZE and junk the engine..>>>Dan ( It will also foul all the spark plugs,,, said with tongue firmly planted in cheek )

 

[BandB]

It won't "sputter to a halt",, it will SEIZE and junk the engine..>>>Dan

That is if you're lucky and no fire or explosion.

 

[KnotYet]

It won't "sputter to a halt",, it will SEIZE and junk the engine..>>>Dan ( It will also foul all the spark plugs,,, said with tongue firmly planted in cheek )

I have personal experience with a gas engine being mis-fueled with mostly diesel.
That engine needed replacing because it was driven while pinging very severely.

The scenario that ofer (the OP) suggests occurs surprisingly often in diesel cars.
I have a VW TDI and so am regularly on one of the forums for those...

It seems that mis-fueling happens often enough that people are familiar with the
outcome. When a load of gasoline is added to a mostly empty TDI tank the car's
engine shuts down due to the gasoline vaporizing either in the fuel pump or the
injectors, inhibiting the necessary hydraulic activity. Something like vapor-lock?

So rather than destroying the engine it may just cease to run and need purging.

 

[BruceK]

I once accidentally put about a litre of gasoline into the 55L tank of a diesel Peugeot 508GT. I reverted to the diesel pump and filled the tank. No issues arose, car engine functioned as normal.
Not something I would do intentionally, car or boat.

 

[ofer]

Well, they can't be good ones.

Only thing dumber than putting the gas in the diesel, is putting yourself in position to even consider that. I hate to even think that you are serious in asking this question.

this thread is not about why i will carry 100 of gas. as i said i have my reasons. i am not stating them at the moment in order not the derail the thread even more.

 

[Blissboat]

I once accidentally put about a litre of gasoline into the 55L tank of a diesel Peugeot 508GT. I reverted to the diesel pump and filled the tank. No issues arose, car engine functioned as normal.
Not something I would do intentionally, car or boat.

Had a similar incident with an older VW TDi. After completing the fueling with diesel, the engine ran without noticeable effects, but you can believe I had my ear tuned every second, and kept topping up with good old diesel at every chance, 'til the witches brew had been burned off. Not a pleasant memory.

 

[Jmarsh203]

Older Diesel engines would cope much better than anything newer in emergency situations but wouldn’t know the max gasoline mixture, rough guess I wouldn’t go over 25% gasoline and I would add motor oil to it. There have been multiple multifuel engines built over the years most being able to use up to 70% gasoline with motor oil added for lubricity with no impact on longevity of motor. They have almost exclusively been designed off of Diesel engines, with the only exception that I know of being a joint effort for the military by evenrude and mercury made an outboard that would run on anything flammable and it had spark plugs but none others do that I know of(btw don’t look for it it’s a complete dog not worth its weight even when running on gasoline like it was supposed to it was unbearably slow/expensive/heavy also nobody would be able to service it since it was sold exclusively to the military) but the trick of every other diesel based multifuel engine I know of is they use super high compression, Like 22:1 high and they add a turbo on top of it and injectors that shoot a stream of fuel instead of atomization. They were never known for economy they were almost exclusively military engines, but Most older Diesel engines will cope with a certain amount of gasoline in the fuel but would be less than ideal. I also wouldn’t stress out or go drain my tanks if I accidentally added some gas to my fuel tanks but I’d never go out of my way to add it either. I’ve got plenty of tankage so running out of fuel is nothing but negligence on my part. Now to dispel the myths and lies by the uninformed There is no chemical reaction to worry about that will blow you up if you mix gasoline and diesel, but boats built with diesels tend to not have blower motors in engine compartments like gas built boats are equipped with so that would Definitly be of concern to me. Lol Also the explanation of octane by star is 100% wrong, octane has nothing to do with explosive value and everything to do the fuels ability to resist knock. Also diesel has MUCH more explosive energy in it than gasoline does if you would like to call it that, which I wouldn’t but judging by some explanations that may be the easiest way to explain it to some so I’ll go with that.

 

[Lou_tribal]

Older Diesel engines would cope much better than anything newer in emergency situations but wouldn’t know the max gasoline mixture, rough guess I wouldn’t go over 25% gasoline and I would add motor oil to it. There have been multiple multifuel engines built over the years most being able to use up to 70% gasoline with motor oil added for lubricity with no impact on longevity of motor. They have almost exclusively been designed off of Diesel engines, with the only exception that I know of being a joint effort for the military by evenrude and mercury made an outboard that would run on anything flammable and it had spark plugs but none others do that I know of(btw don’t look for it it’s a complete dog not worth its weight even when running on gasoline like it was supposed to it was unbearably slow/expensive/heavy also nobody would be able to service it since it was sold exclusively to the military) but the trick of every other diesel based multifuel engine I know of is they use super high compression, Like 22:1 high and they add a turbo on top of it and injectors that shoot a stream of fuel instead of atomization. They were never known for economy they were almost exclusively military engines, but Most older Diesel engines will cope with a certain amount of gasoline in the fuel but would be less than ideal. I also wouldn’t stress out or go drain my tanks if I accidentally added some gas to my fuel tanks but I’d never go out of my way to add it either. I’ve got plenty of tankage so running out of fuel is nothing but negligence on my part. Now to dispel the myths and lies by the uninformed There is no chemical reaction to worry about that will blow you up if you mix gasoline and diesel, but boats built with diesels tend to not have blower motors in engine compartments like gas built boats are equipped with so that would Definitly be of concern to me. Lol Also the explanation of octane by star is 100% wrong, octane has nothing to do with explosive value and everything to do the fuels ability to resist knock. Also diesel has MUCH more explosive energy in it than gasoline does if you would like to call it that, which I wouldn’t but judging by some explanations that may be the easiest way to explain it to some so I’ll go with that.

Hercules made engines able to run on about anything that could burn. They made multifuel mil engines able to run on diesel and gasoline and some folks tried to burn about anything from vegetable oil, engine used oil, ATF oil etc. One guy crossed US on his old mil truck burning his old engine oil on the way lol. One said that ATF oil smell strange when burning but still all this worked.
From what I read, the goal of these engines was to be able to run on anything considering that fuel supply may have been compromised on war zone.

L

 

[Barking Sands]

ofer,


Octane is the explosive value of fuel. Typically Gasoline has 87 (or More) Diesel fuel has about 10 Octane. So Gasoline has about 8.7 times the amount of explosive power of Diesel. Don't do it, it isn't just bad for your engines, they can literally explode like having a grenade go off in each one of your cylinders (with the accompanying shrapnel).



Star

Just an FYI. This is all wrong.


This is from Wikipedia.

In North America, gas stations offer two types of diesel fuel — according to ASTM D975[5] these are named No. 1 and No. 2 fuel. No. 1 fuel (kerosene) has a natural CFPP of -40 °C but it is more expensive than No. 2 fuel. Adding No. 1 fuel will lower the CFPP of No. 2 fuel – adding 10% will lower the CFPP temperature by about 5 degrees.[6]

For some diesel motors it is also possible to add even lighter fuels like gasoline to extend the CFPP characteristics. Some car makers were recommending adding up to 20% gasoline to permit operation in cold weather (at the price of higher consumption) and it had been common practice in Europe where No. 1 fuel is not offered at gas stations. Since the 1990s car makers began selling only direct injection diesel engines — these will not withstand any gasoline portions in the fuel as the high pressure in the injection device will not withstand any loss of lubrication from fuel oil without doing damage to the injectors. High pressure fuel pumps depend on diesel fuel for lubrication and the addition of gasoline will cause adverse wear and eventual failure of the pump.

Car makers selling Common Rail or Unit Injector diesel engines prohibit the dilution of diesel fuel with either gasoline or kerosene as it may destroy the injection device

In an extreme emergency when the long term or near term health of the engine is a secondary consideration I would bet that you could run 25% gas if you could add some additional lubricity and could premix (just an opinion based on anecdotes). But that would depend on circumstances. Do you need to make it 500 miles? 50 miles? Could you risk the loss of the engine or injector pump to completely strand you between here and there? It would seem the higher the ratio of gas you trade off nearly equal proportion of reliability to the point of at some ratio not being able to run at all. So how would that affect your "emergency". In addition adding 25% of gasoline will not result in "stretching" your fuel supply by 25%. Gas has less energy density by volume than diesel of something like 15%. So diluting with 25% of gas might stretch your range only some fraction of that 25% if your scenario was volume limited.

In running through possible scenarios of why one might do this ....It would be a very odd circumstance that this would make any sense at all.

 

[FF]

"I have an aux tank with 100 gal of gasoline.
If I dump it into my diesel tank what would happen?"

Many euro diesel autos use 10% gas added to diesel fuel to make the car easier to start in the cold.VW sez its fine.

I would not go over 10%..

ATF as diesel fuel is fine , it is common in repair shops to fill fuel filters , as its clean , and doesn't present a problem.

 

[rwidman]

What are the options if any on adding gas to diesel to make a few more miles.

any percentage mix that are acceptable and or addling ATF or something like that to the mix.

I see I'm not the first to respond but, DO NOT DO THIS!!!

Call your towing company and ask them to bring you more fuel. Better yet, don't run short in the first place. Plan ahead.

 

[Jmarsh203]

If I was looking to extended the range of my boat, and I had a 100 gallon gasoline tank, I would absolutely run it mostly empty and fill it with diesel fuel. When switching it back to gasoline I would pump the diesel completely out, throw 5-10 gallons of gasoline in it to clean it out and either throw it out or pump that directly into my diesel fuel tank to get rid of the junk mixture than fill the gasoline tank back up with gasoline.

 

[sean9c]

Raise the combustion temps, coke the injectors, reduce lubricity. What could possibly go wrong.

 

[SteveK]

Round and round we go.

Perhaps the OP can proceed with the test and settle the matter once and for all.

 

[ofer]

Round and round we go.

Perhaps the OP can proceed with the test and settle the matter once and for all.

good idea thanks

 

[BandB]

Round and round we go.

Perhaps the OP can proceed with the test and settle the matter once and for all.

And he missed your sarcasm.

 

[ofer]

And he missed your sarcasm.

actually you missed mine

 

[Art]

Actually... Sarcasm has no place and means little when fooling with potential life or death high combustion fuel-in-tanks, then high ignition fuel-inside-engine mixtures.

 

[utclmjmper]

Not to mention the destruction it does to your wallet..>>>Dan

 

[Jmarsh203]

Raise the combustion temps, coke the injectors, reduce lubricity. What could possibly go wrong.

Wrong direction, gasoline will cool combustion temps, diesel is the more energy rich fuel. Cutting it with a less dense fuel will cool combustion temps. Coke the injectors??? Never heard of that before, you thinking wet stacking maybe? Now you are right that it reduce lubricity but all of the multifuel engines add oil to the mixture to add lubricity and I would as well if I was using gasoline/ diesel mixture. None of it is as good as straight diesel

 

[FoxtrotCharlie]

In college in 1975 (MS State U) I bought a used 1971 Mercedes 220D. With three friends we went out West to Tetons and Yellowstone. Got to Denver and thought we were about there - ha. Thought it would be cool to drive through the mountains vs the interstates. Two lane roads, and we were soon low on diesel - stopped at an old service station - they had no diesel, and none was around. Saw a kerosine tank - took on ten gallons of kerosine and added two gallons of gasoline. Ran like a top.

 

[Iggy]

Not the same

Why but use a 5gal can or a bladder for more fuel?

 

[ofer]

In college in 1975 (MS State U) I bought a used 1971 Mercedes 220D. With three friends we went out West to Tetons and Yellowstone. Got to Denver and thought we were about there - ha. Thought it would be cool to drive through the mountains vs the interstates. Two lane roads, and we were soon low on diesel - stopped and an old service station - they had no diesel, and none was around. Saw a kerosine tank - took on ten gallons of kerosine and added two gallons of gasoline. Ran like a top.

we are now at the 80% 20% tested. we are getting somewhere.

 

[Nick F]

I, too, do NOT recommend what the PO has described. However, some of the posts seem a little inaccurate in the terminology, so I would like to try to clear this up. If there is any error in the following, please let me know.

FLASH POINT
The flash point of a volatile material is the lowest temperature needed to evaporate enough fluid to form a combustible concentration of gas.
Diesel: 52C (126F)
Gasoline: - 43C (- 45F)

AUTOIGNITION TEMPERATURE
The autoignition temperature of a substance is the lowest temperature in which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark.
Diesel: 210C (410F)
Gasoline: 247-280C (477-536F)

OCTANE NUMBER
An octane number is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating.
In a typical spark-ignition engine, the air-fuel mixture is heated as a result of being compressed and is then ignited by the spark plug. This burning normally takes place via rapid propagation of a flame front through the mixture, but if the unburnt portion of the fuel in the combustion chamber is heated (or compressed) too much, pockets of unburnt fuel may self-ignite (detonate) before the main flame front reaches them. Shockwaves produced by detonation can cause much higher pressures than engine components are designed for, and can cause a "knocking" or "pinging" sound. Knocking can cause major engine damage if severe.
As a general guide, higher octane gasoline has a higher autoignition temperature.

COMMENTS:
As you can see, you could throw a lighted match into a bucket of diesel fuel at room temperature and it would not light. By contrast, gasoline is so volatile (evaporates readily) that it can be lit at any temperature likely to be encountered.

Interestingly, the autoignition temperature of diesel is some 100F lower than that of gasoline. However, fuel in the bilge is unlikely to get raised to high enough temperature to autoignite. If it does start on fire it will have been the result of a spark and any spark has a temperature far in excess of these autoignition temperatures.

I worked overseas for many years and in Brazil in the 80s there was a shortage of diesel fuel and it was being delivered with up to 15% gasoline content for a period. This did not seem to damage the diesel engines, but made boating much more hazardous because its flash point was below ambient temperature.

Regards,
Nick

 

[Comodave]

As you can see, you could throw a lighted match into a bucket of diesel fuel at room temperature and it would not light. By contrast, gasoline is so volatile (evaporates readily) that it can be lit at any temperature likely to be encountered.

Nick,

Absolutely correct. We were doing crew qualifying and they had to extinguish a fire. The fire chief had a pan of water with some diesel floating on the water. He tried with a lighter to ignite the diesel, no go. Then he tried a road flare, no go. I told him to add half an ounce of gas to it, he said no that was too dangerous. After trying everything he could think of to ignite the diesel he finally added a small bit of gas. Then we threw a lighted match at it and it went right up.

 

[rgano]

At the mix suggested, I would guess the engine won't last long.

 

[Art]

Goodness, goodness folks. This ain't war time. Mixing different types of fuel is dangerous on more than one level and not necessary except in the most strained conditions. Just keep enough of the correct fuel aboard.

 

[ofer]

As you can see, you could throw a lighted match into a bucket of diesel fuel at room temperature and it would not light. By contrast, gasoline is so volatile (evaporates readily) that it can be lit at any temperature likely to be encountered.
.

this is true for any gasoline boat. i get it. it has nothing to do with the mixing factor.