So, to top off the absolutely crappy day I had yesterday, I distractedly dumped 4 gallons of 87 octane gas into my tank before waking from my stupor & topping off with diesel.

There were about 5 gallons of fuel in the tank before I goofed. As soon as I realized what I did, I shut off the truck and topped off with diesel.

The 1 mile drive home seemed just fine. The truck is parked right now until I know what to do.

What, if any, damage could happen to the engine with 4 gallons of gas mixed in a full tank?

Should I drain the tank or just ride it out?

 

You should completely drain the tank. Gasoline could damage parts of your injection system. Some "old time" diesel people used to think adding gasoline in small quantities was OK (in cold weather), but that's not true. This is from Diesel Injection Service:

Mixing Gasoline with Diesel Fuel
At one time information was released suggesting that a small amount of gasoline mixed with diesel fuel for use in cold weather was an acceptable practice. This information was eventually retracted due to conditions that may result from such a mixture.

First and foremost is a safety factor. The gasoline fumes from gasoline are very rich and there is not enough oxygen available for a spark generated at the filler neck to ignite these fumes. The diesel fumes are too lean and will not ignite. A mixture in the right proportion could create fumes volatile enough to ignite from a spark generated at the filler neck.

Second, all injection pumps and injectors utilize the lubrication in diesel fuel to keep internal parts lubricated. Gasoline cuts down on this lubrication and can lead to premature injector and pump wear or even failure.

Although accidentally mixing a small percentage of gasoline with a tank of diesel fuel may not result in an immediate problem, it could still result in shorter pump and/or injector life. The only safe action would be to drain the mixture and start from scratch. While this may seem costly, it could save you from more costly repairs in the long run.

 

Dumping (recycling) & replacing would be the correct thing to do... I would even call the Service Dept. and ask their advice. With between 10% and 14% of gas now in your Diesel system, depending on what size tank you have. I know some marine places out here run old diesel through filters to remove impurities & put it back in the boats with stabilizer. They call it "Polishing".

But I 'wonder' if you added a stabilizer with lube, ran the tank down to about half, added more diesel and ran that down again and then changed your fuel filters if that would minimize possible damage?? I ran a search on Yahoo & a PSD owner suggesting adding 1/2 gal vegetable oil for lube purposes.. I don't have a warm fuzzy feeling about that one..

You're not the first to do it & won't be the last...

I hope others that have done this before can give you some helpful advice..

Good Luck,

Russ

 

I would recommend draining the tanks also. Gasoline is lighter than diesel so it SHOULD be floating on top of the diesel, so you will have to completely drain the tank. Might give your dealer a call and talk to your service advisor. They'll be able to quote you a price for this service and/or give you some good advise on how to do it yourself. On the other hand someone here can probably give you the same advice on how to drain/remove your tank, and Ford will never have to know there was gasoline in your tank.

 

That is an expensive motor to risk. I would siphon it out since there is no drain plug on the tank. But what about draining what got sucked into the injection system already. I would remove/replace both filters and drain as much as possible. Then replace with fresh filters and clean diesel.

 

BTW, my wife and I have matching trucks. Both our King Ranches are identical except mine is the PSD and her's is the V-10. I worry that some day she might accidently GAS up my diesel. I think I might put one of those locking fuel caps on the tank so she'd have to think twice before fueling up.

 

I'm "old time diesel people" and I still don't like mixing gasoline with diesel.

In 1985 we were on vacation in Michigan's U.P. One morning I was filling up the tank with diesel for a trip to Macinac Island. As I was filling the tank I kept smelling gasoline. Worried, I double checked the nozzle. Okay, it's the right one, oily stains and all. Still kept smelling gasoline.

Tank full, I hang up the nozzle and still being curious, begin a slow eyeball inspection of the pump island. That's when I notice that the diesel pump I filled with was marked "DIESELINE"! I checked with the clerk to confirm. Yes, he says, it's a mixture of diesel and gasoline blended for the upcoming cold weather. D'oh! I didn't need that!

Well I could tell the difference in the fuel. It had less power on hills and the diesel 'rattle' was a little more tin'ey sounding. It didn't seem to hurt anything, but I didn't like it one bit! As soon as it was down to 1/2 tank I refilled with good diesel and did the same thing again once it was down to 1/2 tank.

BTW, gasoline and diesel mix. Although true, gasoline is lighter than diesel it won't float on the diesel. If fuel was that easy to fractionate, we wouldn't need no stinking refineries!

 

Funny that you mention calling the service rep. I did that (without telling them who I am) and he said, "Eh, if it were my engine, I wouldn't worry about it." Somehow, that didn't give me a warm, fuzzy feeling.

 

definatly - drain the tank!!!

 

and drain and change the fuel filters. Cheap insurance. You can get some Stanadyne additive that is for injectors and fill the cup of the fuel filter on the engine then cycle the key on 30 secs off 15 three times then start it on the fourth.

Cheap insurance.

 

Well bz919, do what they are saying, drain the tank!! And the fuel lines and possibly a new fuel filter, and judging by an answer like that, I'd be changing dealerships too!

 

I would get the Lubricity Formula in this case.

 

Thanks, Johnsdiesel, that was the product name I was looking for. Instead I did a brain cramp.

 

I did all of the above yesterday morning...had the tank drained, the fuel lines purged, the filters replaced, AND switched to another Ford dealership that, as it turns out, has a truck/diesel repair shop. Definitely won't be going back to the other one any more.

Thanks, everyone, for all the advice.

I'm a few hundred dollars poorer, but hopefully a bit wiser too

 

Glad it worked out. Did they give you any advice on long term problems to expect or say all is ok?