Help! I put Gas in my Diesel truck


#1

I’m looking for advice. I drove my truck 1 mile to the dealership where it sits now, waiting to have the gas drained out. Do you think the injectors will need to be replaced??


#2

I doubt you did any damage to the injectors (or anything else) in one mile. Was there also diesel left in the tank? How did it run while you were driving it? If it ran without any ugly noises and the dealer drains the gas out, I think you will be OK.


#3

If the engine continued to run you might be lucky and there will be no damage.


#4

Thanks for your input. There was diesel left in the tank also so we’ll hope for the best!


#5

I agree that there should be no damage. Both are very similar with the exception of the octane. Gasoline doesn’t detonate as readily.

Had you done the opposite and put diesel in a gas engine you might have a problem because diesel would preignite.

  • mountainbike

#6

Both are very similar with the exception of the octane. Gasoline doesn’t detonate as readily.

Had you done the opposite and put diesel in a gas engine you might have a problem because diesel would preignite.

I hate to be picky, but that is really not true. Gasoline and diesel are not at all similar, they have completely different combustion characteristics (gasoline burns much faster than diesel). Also, it is meaningless to talk about the octane of diesel, the relevant measurement for diesel is cetane, which is actually the opposite of octane. Finally, gasoline is much more prone to detonation than diesel, diesel engines operate at about 20:1 compression ratios, even the highest octane gasoline will detonate at a any compression ratio over about 10:1 or 11:1. Diesel fuel will not even self-ignite in a 11:1 engine.

Burning gasoline in a diesel engine can cause significant damage, a diesel engine is designed to inject the fuel near the end of the compression stroke so it will combust slowly throughout the power stroke. Injecting gasoline can result in a rapid detonation, possibly before the piston reaches top dead center. Folks have been know to bend connecting rods and cause other damage. BTW, it is also not advisable to use “starting fluid” in (indirect injection) diesel engines for similar reasons. It is likely that a gasoline engine simply would not start on diesel fuel.


#7

I believe that I can reply to your question with an experience rather than conjecture or baseless opinion. Several years ago I unwittingly put about 5 gallons of regular gas into my older VW diesel before I saw my error. I had little choice but to continue filling with diesel and then go home about 3 miles away. The engine made no odd sounds. I then syphoned the tank empty as possible into gas cans and then, without additional driving, filled the tank with diesel fuel and a dose of an injection pump lube. I ran the engine without driving for a few minutes to get the fresh mix into the pump and drove away. I slowly used up the gas/diesel mix later. That was about 50,000 miles ago; still no problem. Older VW diesels, and it’s in my owner’s manual, allowed as much as 30% regular gas in diesel fuel in the winter to dissolve jelling. Go without worry!


#8

“I had little choice but to continue filling with diesel and then go home about 3 miles away. The engine made no odd sounds.”

Your engine never tasted any of the gasoline…Three miles is not enough driving to burn the pure diesel in the pump, filter and fuel lines, even with the pump return flow…

30% gasoline for winter driving? How about 5% max…The preferred winter diesel fuel additive is Kerosene. A 5% mixture will prevent fuel gelling down to 40 below zero…


#9

I don’t agree. Another time I got my diesel started at 10 below zero. It took a little over a mile for the engine to stop due to jelled fuel. Again, my owner’s manual for an 80s VW diesel allows 30% regular gasoline in the winter. This question has come up repeatedly on Car Talk.


#10

Quoted directly from the VW owner’s manual from the mid 1980s: Only if neither No. 1 Diesel Fuel nor winterized Diesel Fuel No. 2 nor Kerosene are available, use up to 30% leaded or unleaded gasoline. Do not use Premium gasoline.


#11

I’m not sure about VW’s recommendations, but prior to about 1980 benz recommended adding some amount of gasoline to diesel for winter operation. They later changed their recommendation to mixing in #1 fuel oil (similar to kerosine). The amount to be mixed in was depended on temperature.

I agree that relatively small amounts of gasoline will not cause damage. Some folks who burn vegetable oil add a significant percentage of gasoline to reduce the viscosity of their “fuel.” The problem is running a large percentage of gasoline, I don’t know how much would actually cause a problem.


#12

That engine needed glow plugs to start, not a direct injection engine, so it might tolerate a high percentage of gasoline. Combustion chamber design plays a very important role in what fuel a diesel engine will operate on. It took Rudolf Diesel YEARS of cut and try work before he got the fuel, timing, compression ratio right. He was badly injured when one of his test engines exploded…

I’m sure there are diesel owners out there that can tell gasoline mistake horror stories involving broken pistons and bent rods…


#13

I have been following VWVortex.com and TDIClub.com for about two years; never heard of a problem with a blown engine due to gasoline use. Never!


#14

PS, VW has had direct injection diesel engines since 1993.


#15

It’s probably less of a concern with direct injection engines, but it’s still not good.


#16

Thanks again, you were right. They only had to drain the tank and such, no harm to anything else…an expensive lesson to learn - $696.