Running 2 cycle fuel in a 4 cycle engine

[Joe Warren 75]

A guy I know runs all his 4 cycle power equipment engines on 2 cycle fuel. He claimed it reduced engine wear. Aside from the added cost of the 2 cycle oil, are there other downsides. Just curious what you all think. 

 

Joe 

 

And now for the rest of the story: I spoke to the guy again. He was a mechanic at a place where they operate a lot of outdoor power equipment; with both 2 and 4 cycle engines. To prevent employees from putting straight gas into their 2 cycle machines, all their fuel got 2 cycle oil mix with it. For them, it was more economical to spend money on oil, than on blown engines and downtime. 

 

Thank for all the great posts. I found some to be very entertaining.

 

 

Edited March 22, 2021 by Joe Warren
Follow-up, added information.

[DennisThornton 4,769]

I'd suspect some smoke and early fouled plugs.  2 cycles have to get all their lube oil from the fuel, 4 cycles don't since they have a crankcase.  What would the 2 cycle oil lube in a 4 cycle?  That the crankcase oil doesn't?  My 1.5 cents.

[stevasaurus 22,717]

So, that is who is polluting the planet.  

[SylvanLakeWH 25,535]

Smoke is the only impact I  see from doing it... 

 

[Ed Kennell 38,143]

When I winterize my boat motors, I drain and save  the mixed gas.    I save some for chain saws and string trimmers and the rest  I dump a gallon of the mixed in my vehicles when I fill the tanks.   The gas/oil ratio is then  1000/1.     No problems

[R Scheer 502]

I've heard of people adding 2 cycle oil if they're starting the engine after sitting idle for a long time, but for normal use it sounds like a lot of smoke, fouled plugs, and carbon buildup in the cylinder head. 

 

JMHO

[Pullstart 62,837]

Is this premixed from jugs, or two cycle out of a can fuel?  I imagine a hotter plug might take care of the excess oil.  After all, a 4 stroke with worn rings likely burns more than 40:1...

[lynnmor 7,305]

I needed to move my Dads tractor, with an Onan, after he passed but it was out of gas.  All that was there was an old mix for his chainsaw so I dumped that in, I expected to see a lot of smoke but their was none, it did run poorly though.

[gwest_ca-(File Mod) 11,040]

We could not get Marvel Mystery oil in Canada for a couple of years because their labels did not meet requirements. I used 2-stroke oil instead and could not see any difference.

 

Garry

[Gregor 4,846]

3 hours ago, DennisThornton said:

What would the 2 cycle oil lube in a 4 cycle?  That the crankcase oil doesn't? 

Carburetor innards maybe? Upper rings? How do the valve guides get oil in a 4 stroke? IDK  I'm just throwing out ideas. I have seen what happens when you str8 gas a 2 cycle. You don't want to do that.

[gwest_ca-(File Mod) 11,040]

I use it to lube the valve stems. There is a bit of a skip in the exhaust without it and gone with it.

 

Garry

[DennisThornton 4,769]

1 hour ago, Gregor said:

Carburetor innards maybe? Upper rings? How do the valve guides get oil in a 4 stroke? IDK  I'm just throwing out ideas. I have seen what happens when you str8 gas a 2 cycle. You don't want to do that.

Cylinder walls get splashed with oil so the rings run through that.  I assume the same for the valve guides.

[TJ5208 1,824]

If you like smoke go for it

[bc.gold 3,403]

Ashless 2-Cycle Engine Oil

[Gregor 4,846]

My dad was an airplane mechanic in the Air Force. He claimed MMO was the best thing that ever happened to an engine.

8 hours ago, gwest_ca said:

We could not get Marvel Mystery oil in Canada for a couple of years

 

[Skipper 1,788]

I use Castrols fully synthetic 2 stroke oil at end of season on often used machines, and always in machines that just sit a long time between use. It stabilize the fuel very very well. I have not had a single carb issue since I started using it. Buy the right stuff, and there is zero smoke, smell or fouling. Only thing I can imagine it also does, is lube the engine a bit more. That newer was a bad thing though...........

 

But why don't you just buy some chemicals in a can and mix in instead? you might ask.

 

Well, I can use something that surely wont harm the engine in any way, perhaps even just help it a little instead, or I can try my luck with some jug of chemical miracles............. I know what I favor 

 

Just my  and experience, over the last 4 years and a lot of machines that get stored for many months before next fire up.

[ranger 1,750]

I was always warned against adding extra oil to the ‘recommended’ ratio/mix in the older two stroke motor bikes, the reason given was, “More oil through the same size jet, means less petrol and a ‘weaker’ mix”. This was said to increase the risk of overheating, burned pistons and possible seizure! I shouldn’t think this would really apply to our horse’s power units under normal conditions, whatever they are? I suppose you can always adjust the mixture to suit? Add some Castrol ‘R’ to the tank, as we used to, to get the smell of the race track! 

P.S. Might mess up your 🐈  🙀

Edited March 21, 2021 by ranger

[JoeM 7,873]

I figure the crankcase vent tube to the carburetor is plenty of oil vapor for the "top end"

 

Most two stroke oil would probably burn off. Don't forget the two stroker oil enters the crankcase on intake first. 

 

I figure most of my engines are going to out last me just using non e fuel. 

 

[Gregor 4,846]

Sort of on topic. Maybe someone can answer this. On old 2 stroke Lawn boy engines there are several types of course. A C-19 has a piston with 3 rings. No,what I would call an oil ring, like you would find in a Kohler, just 3 basic rings. A D-600 only has 2. Just basic rings. You can swap the 2 ring piston, for the 3 ring piston, if you change the rod. The jug remains the same. If you do swap, you are to use a 32-1 mix, instead of the 16-1 mix, required by the 3 ring piston. I have never understood the why of this.    ???????

[bc.gold 3,403]

52 minutes ago, Gregor said:

Sort of on topic. Maybe someone can answer this. On old 2 stroke Lawn boy engines there are several types of course. A C-19 has a piston with 3 rings. No,what I would call an oil ring, like you would find in a Kohler, just 3 basic rings. A D-600 only has 2. Just basic rings. You can swap the 2 ring piston, for the 3 ring piston, if you change the rod. The jug remains the same. If you do swap, you are to use a 32-1 mix, instead of the 16-1 mix, required by the 3 ring piston. I have never understood the why of this.    ???????

 

Rings also act as scrapers with the 3 ring piston the richer 16:1 mix was required to leave sufficient lubricating film on the cylinder wall.

Edited March 21, 2021 by bcgold

[Pullstart 62,837]

Anyone ever heard of adding a splash of ATF to their fuel or oil?  I’ve mentioned this before but a high school auto shop teacher taught me.  ATF has a high level of detergents in addition to extra lubrication properties.  I am never afraid to run as much as a quart in a full tank of auto fuel.  A little less mixture to small engines, based in tank size of course.

[Gregor 4,846]

2 minutes ago, pullstart said:

Anyone ever heard of adding a splash of ATF to their fuel or oil?

I have often wondered if MMO is ATF.

[chucksterock 15]

I mix my leftover race gas mix 50:50 with straight gas to burn up the old mixed fuel.  Smells really good mowing with more than a hint of race gas and no smoke.  I run Klotz super techniplate oil which is a mix of synthetic and castor.  Plus the wife likes the smell too.

[tom2p 2,394]

I will sometimes dump a little premix in the tank of the Wheel Horse tractors when I fill them ... just a small amount 

 

on a Kohler powered 312 and an Onan powered 416 

 

been doing this for over 20 years 

 

have anyone compared a 2 stroke fuel system (carb, lines, tank) to a 4 stroke ... ? ... after sitting ?

 

a little oil goes a long way 

 

Edited March 24, 2021 by tom2p