Diesel contamination of a gas tank

Factual Questions
1

Because that is what has happened to me. Mods, some GQ’s coming up after I quickly outline the story…

I had been getting an engine warning light coming on over the last 2 weeks, and my engine had seemed to have been running a bit rough this week. 3 days ago the light went out. I was scheduled to have the Goodyear service guys take one last look at it yesterday morning, brought it in, and long story short the car seemed ready to go based on their professional opinion (they had already run two sets of tests on it, they found nada).

I then go to pick up my mom’s mail from her nearby condo. Her parking space is on an upward incline. Go in, come back out-and now the engine won’t turn over. Plenty of battery juice, it would just sputter and not start.

Got it towed to my dealership, thinking they might need to reset the computer or something. He called me an hour ago, and said that DIESEL had somehow contaminated my fuel tank! Now I’m looking at $700 to drain the tank, drain the fuel system, and replace the fouled spark plugs.

Now I KNOW I have never pumped any diesel into the thing, ever. I ALMOST did about 6 months when I went to an unfamiliar station, but quickly caught myself when I was about to grab the wrong hose (which is typically colored green).

So, GQ. My theory was that a small amount of diesel contamination was present in each tankful that I had put in previously. But, over time, the diesel would accumulate at the bottom of the tank (since diesel is denser than gasoline, and my car needs premium). It finally got undiluted enough in that thin layer to get into my fuel pickups, esp. given that I was parked on an incline (I’m not sure if my vehicle has the pickups at the back or front of the tank-2006 Honda Civic SI here). All the pumps I’ve seen always have the diesel ones on a completely separate hose from the gasoline ones. I was also on a quarter tank yesterday, FWIW…

My understanding of the refining process is that the fuels are laid out in layers, denser ones on the bottom, lighter ones on top, and are drained out by hoses set at the appropriate heights. But a tiny bit of contamination might have perhaps “snuck up” the refining tank thing.

Sound plausible? Otherwise I am out of airspeed, altitude, and ideas. I do know where I had been going to get fueled up lately (a Mobil station near where I live), and will not be going there anymore. If the contamination was limited to that one location, or at least to that specific brand name, then all well and good looking forward (I hope).

2

Gasoline and Diesel will mix no problem.

$700 to drain tank and plugs? Jeeze Louise. Find another shop. Guess those boats don’t pay for themselves. What kind of car is this? A small amount won’t hurt anything. Drain the tank and install gasoline. It may be a good plan to replace the plugs, but I’d run a tank or two of gasoline through and see how they look.

If you are handy enough, it won’t cost you a dime, other than the diesel itself.

3

He whole idea of contaminants collecting at the bottom of a gas tank is a meme that will not die.
The fuel pump pickup is at the bottom, so nothing can accumulate there.

4

There is a certain amount of unusable fuel in a given tank, maybe a gallon or so. Water and other contaminates that are not miscible would tend to collect there, but diesel and gasoline will mix.

Through an extremely unlikely series of events, a cascading series of failures, I have installed a full tank of diesel in a gasoline vehicle. It’s not that big of a deal. It needs to be drained as best as possible, and that should be the end of it.

Note that the opposite - gasoline in a diesel, IS a big deal and will quickly ruin the injectors, pumps and other gee gaws and I don’t know what all. Years and years ago Diesels were basically omniverous, but not anymore.

5

as has been said, diesel and gasoline are both petroleum-based and will thoroughly mix.

I would ask for a sample of the fuel in the tank (watch them draw it out too.) Diesel fuel smells pretty similar to kerosene.

you didn’t say how old your car is, but it really shouldn’t be easy to put diesel in a gas car. Since the ban on leaded gas, cars requiring unleaded have had a restrictor in the fuel fill neck to prevent anything but a gasoline pump nozzle from being inserted. unless a cheap-ass station put a gas nozzle on a diesel pump, it shouldn’t have been possible to insert the diesel nozzle into your tank.

I’ll just say that I generally don’t trust “chain” auto shops. If your check engine light had been on, there should have been stored DTCs, did they pull any codes?

mixing a small amount of diesel into a gas car’s tank might not be noticeable, but as you add more it’ll initially start reducing the overall octane rating, and after adding enough it won’t be volatile enough to be ignited by spark.

6

I mentioned the make model and year in the OP.

Well, that’s what I hoped they would do, run the computer and see if there is anything wonky there (hardware or software).

The not trusting a brand name chain shop is precisely why I had been reluctant to go there, since I have had a few slightly irksome irregularities with said chain shop (I switched to the local Goodyear garage a few years ago for precisely that reason, and in this particular case they could have given me a big spiel about some nonexistent problem and charged me a grand, but they didn’t do that).

So, again, the question of how it got in there remains utterly unanswered, since apparently my WAG in the OP cannot happen. The cap can only be opened by a lever on the inside. Like I said, I put in a full tank of premium about a week ago, and obviously I was able to drive it around with no issues until yesterday.

7

Google is my friend…
Bad Fuel: Fact or Fiction?

Apparently things aren’t as simple as just draining the tank, and off I go…

So, if true, who should I go to? A government agency? The local press? I probably should not talk to the local gas chain district manager. Yeah, I’d like to get my repair money back in other words…

8

Google may be your friend, but diesel fuel is not polymeric residue. So I take it you are from Indiana, and this the true cause of the late unpleasantness?

You should have receipts showing your purchase of contaminated fuel. You may require the assistance of an attorney. Maybe talk to your insurance agent, they may be able to help. You’ll have to (or somebody will) talk to the manager of the station, they will be responsible (hopefully) for repairs and damages etc.

9

Didn’t something like that happen last year, too? Again, in Indiana via the Whiting refinery?