Can You Use Used 4 Stroke Oil in a 2 Stroke Engine?

[@anthonyg6221]

I have an 80cc (Actually 66cc) motorized bike that I built 5 years ago and I've only run used motor oil in it. I've put at least 4,000 miles on it. Around the 2,500 mile mark, the piston started closing the gap on the plug. I found the wrist pin roller bearing and wrist pin had failed. I installed a new pin, bearing and piston in the original jug and it's been fine since. The engine kit cost me $100 on EBAY. I've saved at least that much, if not 2-3X, vs paying for 2 stroke oil.

[@RealInventions1]

i use like a 50/50 mix of new two stroke and new 4 stroke oil for the fuel mix works fine

[@clutchdroptv4345]

I've been running 5/30 fully synthetic at 40.1 for atleast 10 year's in everything from sthil to China engines and never had any problems my mac saw has 1000s of hours on it of flat out use and I've never even changed the plug

[@northernoutdoors9966]

@@clutchdroptv4345 I’ve still never had any issues

[@Africa1000]

The engine cannot tell the difference between 2 stroke oil and say SAE 30 4 stroke oil. If you get the ratios right it will run fine

[@fonzi0243]

Of course you can but wouldn't really want to because of all the metal shavings in the oil... The whole reason your changing the oil in your 4 stroke is to get that metal out to prolong the life of the engine

[@owenthepug]

I have done this but with clean oil

[@FabioAS]

I'm trying to find a good relation from gas to four stroke oil without damaging my two stoke brush cutter engine. I'm using new 20w 50, but seems to be somewhat heavy, so I think it needs to poured less oil than with normal regular 2 stroke to run smooth in engine. In your case I think you putted too much oil with not enough gas. I wouldn't use used oil, will dirt the filter and carb.

[@northernoutdoors9966]

I haven’t had any issues. I now just use a little leftover new oil from when I do an oil change in the car. I do run it a little lean and it does run better. That being said in my other 2 stroke engines I always run 2 stroke oil. I just thought it would be a fun experiment to try on a free weed eater I got.

[@Africa1000]

How will it affect the air filter?

[@timholstpetersen79]

Try redooing the test, getting the ratio (e.g. 50:1) right... just to let us see the result 🙂

[@timholstpetersen79]

I've been running my chainsaw using 4-stroke oil (instead of 2-stroke) for years without problems. Like you stated yourself, this was NOT a scientific test.... and indeed, I guess you poored way too much oil in there ;-)

[@Africa1000]

Definitely. There is zero evidence anywhere which proves that 4 stroke oil ( mixed to the appropriate ratio) does any more harm than 2 stroke oil does. I strongly suspect that a lot of this talk is mass brainwashing by profit driven oil tech companies. I've yet to come across one example where properly mixed four stroke oil has damaged a 2 stroke engine.