I think I broke my dad’s Echo 302s chainsaw

[adam8aker]

I use my dad’s old Echo 302s, and he gave me a partial quart of grey TruFuel (4cycle) to go with it.
I bought another can of the same stuff when it ran out, but now the saw only runs for a few minutes before quitting
I just realized this is a 2stroke engine and needs mixed gas. I’m seeing 20:1 and 50:1 ratios online, which one is right for this vintage saw?
also, did I dodge a bullet since it still starts, or is the damage already done?

 

[STIHLTECH]

Probably, yes. The best way to find out is to pull the muffler and look at the piston to see if it is scored.
Does it seem to have less compression than it did? Does it pull over easier than it used to?

 

[HArborist2]

Absolutely, I'll do what @STIHLTECH said to pull the muffler and find out