Accidently added oil to gas tank

Someone I know accidently added 1 quart of 5W-30 motor oil to her car’s gas tank. (I won’t get into how or why it happened.)

It’s a 1994 Pontiac Firebird with 3.4 liter V6 engine.

Right now her gas tank is near empty. If I use gas cans to fill up her car’s gas tank, would it be O.K. for her to drive the car? Or do I need to drain the gas tank?

It would be safer to drain the gas tank.

I’ve heard of people accidentally pouring oil into their tank (actually oil/gas mix thinking it was pure gas) on older carburetor-style cars and nothing really bad happened. I think they fouled the plugs a bit but other than that no biggie.

On a modern car though, I’d be worried about clogging up the fuel injectors. 1994 is new enough that I think it probably has injectors and not an old throttle body.

I’d drain the tank.

I’d take my chances filling it with gas. It’s a 15gallon tank. that’ll make it a 60-1 fuel mix. I’ve never had any issues ‘disposing’ of 2cycle mixes into older cars gas tanks. I’m more reluctant with fuel injected vehicles.

I’m pretty sure a 94 firebird still had a carb.

I can’t get past how or why it happened.

Oh come on, you’re in a safe place. Inquiring minds really want to know.

It did not. By 1994 every new car sold in the U.S. was fuel injected.

Fill up the tank and drive it. There’s a hell of a lot of difference between running straight motor oil through the fuel system and running it diluted 60:1 in gasoline. For additional peace of mind, add a bottle of Techron additive after it gets down below half full.

This reminds me of the time I sleepily poured an entire gallon of windshield wiper fluid into my oil tank, and didn’t realize it until my car stopped right on the highway. Many Shubs and Zulls knew what it was to be roasted in the depths of a Sloar that day, I can tell you.

Agreed with Gary_T.

I’ve done it before in my car (2002) by grabbing the wrong jerry can (I keep oil in a yellow one now or in its original containers). It’ll be fine. Just dilute it and when it gets to half a tank, fill up again, repeat. I have injectors and they didn’t get clogged from it. Agreed also on the additive, GumOut fuel injector cleaner works as well. I had no issues.

I can’t help but suspect that a 23 year old engine is already burning oil. A quart of oil in a tankful of gas isn’t that much.

Thanks for the replies.

Yea, it’s fuel injected.

It’s my daughter. She’s 19 and knows zilch about cars.

Last weekend I helped her move into college. The school is four hour away. She has her car with her. I gave her two quarts of oil and a gallon of windshield wiper fluid and told her, “Keep these in the trunk of your car.”

I screwed up in two areas:

  1. I didn’t tell her what the fluids were.
  2. I have never shown her how to check/add oil or fill the wiper fluid reservoir.

So yesterday her (parked) car was very low on gas, and she wasn’t sure if she could make it to the gas station. She thought those quart bottles of fluid were “emergency gas.” After adding the first quart, she said she got a feeling the fluid in the bottle was not gas. So she called me. :o

I’ll be driving up there this Wednesday to help her out. I’ll bring some gas cans and will fill up her tank with fresh gas. I am also going to install a new battery. (Battery inexplicably died, too.)

I think you might mention, that “windshield wiper fluid” is not the same as “distilled water” that is added to lead-acid batteries :wink:

Contrary to the Quora article, I expect that a quart of oil diluted with a full tank of gasoline will not be a problem. The filter won’t stop the oil because it’s not solid, it’s a liquid - and as long as it’s reasonably well-mixed with the gasoline, the viscosity shouldn’t present any significant challenge to the fuel pump. It also won’t “clog” the injectors, since, again, oil is not a solid.

The zinc and phosphorus in the oil are bad for the catalytic converter and for the oxygen sensor, but this shouldn’t be catastrophic. Most owner’s manuals will tell you that your car can burn as much as one quart of oil per 1000 miles before the engine needs to be repaired/rebuilt, so you can look at this as if it’s aging the cat/O2 sensor by just 1000 miles (these should both be good for 100K+ miles). A new O2 sensor may cost a couple hundred bucks installed, so really you’d only be sacrificing a few bucks’ worth of sensor life; this does not justify spending a couple hundred bucks to get the tank drained.

It’s a father’s job to teach daughters life skills, and among them is basic car maintenance. By the time my daughter went to college she knew how to check the fluids and air pressures, and she could even change a wheel.

None of this stopped the plaintive phone call (from 120 miles away) that the car had juddered to a stop. Yes there had been a red light on for a while, and she intended to ask me about it. The engine was seized and the car scrap.

Good for me to see these posts- my daughter is about to head out in a few weeks (but sans car for at least a year is the plan). Still, sound practice.

That is too funny.

Sort of reminds me of this gif.


I for one car I disconnected a fuel line and by cycling the key from off to on, was able to get the fuel pump to run, pumping fuel out into a container. I was able to drain about 10 gallons this way, though you would not want to run it dry. Perhaps you can siphon gas out as well before you add new gas.

I remember as a teen the first time I changed my car’s oil, draining it, swapping filters, pouring 5 quarts back in, hopping in to go for a drive and the transmission lever swinging uselessly and without purpose. I then had to call a friend to take me back to the auto parts store to buy transmission fluid I’d mistakenly drained and five more quarts of oil to replace the 10 now in the engine.

Y’all do make an excellent point about educating young drivers about the basics of car maintenance. I think the kid and I just might have “the talk” this Saturday morning. Just one more in a long line of checklists.