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2 cycle oil - 4 cycle oil

Melensdad

Melensdad

Jerk in a Hawaiian Shirt & SNOWCAT Moderator
Staff member
Over in another thread, BigDog got a Stihl Kombi tool system that has a 4 cycle engine. But you have to mix the gas and the oil. Honestly I have no clue what type of oil he needs to mix with his gas, but I got a brain cramp thinking about it and confused the heck out of myself. Bear in mind, I do understand the difference between a 2 cycle engine and a 4 cycle engine. My confusion is realated to the chemistry of the oil.

So for small engine idiots like me, can someone please explain in simple English:
  • Other than "blue" and "brown" what is the difference between "2 cycle oil" and "4 cycle oil?"
And as a follow up set of questions, without damaging the engine:
  • Can you run a small 4 cycle engine using 2 cycle oil?
  • Can you run a small 2 cycle engine with a gas/oil mixture that contains 4 cycle oil?
 
B_Skurka said:
BIMP
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Well, you use 2 cycle oil in 2 cycles and 4 cycle oil in 4 cycles! But for that hermaphrodite weedeater I guess it could go either way.

Realistically I think you want to use only 2 cycle oil in it because 2 cycle oil is formulated to burn cleanly when blended in gasoline and consumed as fuel.

Crankcase oil won't necessarily burn without residue.

I don't see why 2 cycle oil couldn't be used as a low grade crankcase oil if it is labelled 30 weight, like the old 16:1 outboard oil was. I don't think I would do this for more than just topping up when the oil is expected to be changed soon since it doesn't have the right additives.

I've done that on an oil-burning engine when I was young and poor.
 
I can spell oil but know little more about it.

I do see on some of my 2-cylcles that it says to not even use 2-cycle outboard motor oil so there's some differences.

If you mix crankcase oil in gas at 50-1 will it separate?
 
No, or a least very slowly if it does.

Perhaps, I'm imagining things, but I'm almost positive I remember older chainsaws listing 2 mix ratios; something like 40:1 for 2-cycle and 25:1 for engine oil. Even if I'm imagining it; I know of one old 2 cycle saw that'd ran most of it's life on engine oil and is still going. :o :D

I'm sure that 2-cycle oil is now developed to the point where it does have superior ability to deposite itself on crankcase components while in atomized form.

I'd say California nailed though, with 2 cycle probably buring cleaner, and 4 cycle probably lubing better (in it's liquid form anyway); it makes sense to use the right one for the job.
 
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