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Weed whacker gas in the car

I have a gallon of left over gas that I used for my weed whacker. The gas has approx. 2 tbls of 2 stroke engine oil mixed in (50:1 ratio). Would it do any harm to put it in my car?

I wouldn’t introduce gas that contains oil. If it were a carburated vehicle it wouldn’t be an issue. But on a fuel injected vehicle I would’t run the risk of the oil forming deposits on the tips of the fuel injectors.


Do you have a lawn mower or snow blower?

I wouldn’t put in it my car. Sure, it’d probably run ok, but like said above it might form a partial blockage of a fuel injector, it could clog up your fuel filter, or it could damage your catayltic converter. All in all, compared to the expense of fixing any of those, definitely not worth it. Give it to a neighbor who has a weedwhacker. It could probably be used in a lawn mower or something like that too.

It is no problem what so ever. As long as the gas is fresh and you poor it in with a full tank filled up to dilute it more. If you have a twenty gallon tank, 1/2 a gallon at 50 to 1 becomes a mixture of 40 times 50 to one or 2000 to one. A can of Marvel mystery oil or what ever other glop.or useless additive some one can buy over the counter is much greater. DONOT use old gas. That is the real problem. Two stroke oil is not like motor oil in is ability to dilute. Have no fear. I have added this stuff to my 4 stroke outboards just before storage well as cars and trucks.
I agree with Joeseph though that if you have any trepidation about adding it to a $30k car, dump it into a five gallon can of gas for your other 4 stroke toys and machinery.

I surely would not be afraid to use it. 2000 to 1 gas to oil is nothing to worry about.

Dont worry about it. It will not cause any problems.

On every fuel cap it say’s “Unleaded Fuel Only”

Gee? I wonder what that means?


Tester, I am sure the weedwhacker gas is unleaded.

I have been doing this for tears, never had any fuel injection problems and I keep my cars for a long time.
The last 6 years before I retired I drove for Yellow Freight, over the road. When they changed the oil in a truck ( I think it was 48 quarts ) they dumped it in the fuel tanks of that tractor. They ran lousy for that tankful but didn’t seem to suffer any permanent damage

At the end of summer, I routinely put 2-cycle gas left over from my weedeater into both of my cars. Granted, I only add it when the tanks are nearly full (10-20 gallons). Never had a problem. Heck, nowadays I don’t know how else you’d get rid of it other than burning it in another engine.

I wouldn’t be concerned about injector or combustion problems as long as it’s well diluted, but I would be concerned about the added oil creating deposits on my cat converter insides. I’d recommend against using it.

$3 worth of gas could cause you $lots of problems. Dispose of it with your waste motor oil or old paint if you can recycle. Not worth ruining even a small part of a modern engine, big stuff (O2 sensor, other sensors, CATs, injectors, whatever) clearly would be a bad thing. Offer it to your in-laws. Rocketman

As you can see by now, no one really knows the answer. You can choose from the various guesses. My choice would be to accept the advice from those who have actually tried it. That is, no harm will be done by adding small amounts to a full tank. Go for it!

Do you have a snowblower? You could mix it in 50/50 with the fuel you add to that.

The truth is, fuel injection is much less suseptable to some fuel problems then carbs of old and now. Outboard motors with carbs will become dinosaurs as fuel injection controlled by computer deals with " crap for gas " more easily. Diesels burn only “oil” and they have fuel injection. I know the systems differ, but by much less then you think. Imho, FI under pressure tends to be self cleaning. I feel Carbs which depend on vacuum and have very smaller orifices are much more suseptble to problems…

Also, I would tend to think that the moisture in a tank would create more of a problem. Give me a few ounces of oil to water any day.

Go for it. I have put as much as 10 gals of mixed gas in a Fuel injection car/truck. It will go thru the fuel fillter just fine. We do it all the time around here. My last truck (1997 Chevy 5.0L V8 4X4) had over 335000 miles on it, I ran mixed gas in it more times than I can remenber.Never evan had to change the O2 sensors Ran fine. I would sill have it if I could have made the tail lights and dash lights work stay working. It wont hurt the cat at all, the cat can handle oil burning. Just think if you went thru a QT of oil every 1000 miles. Thats a lot more oil than whats in mixed gas. Also that amount of oil burning is ok with some car markers.