I dont think it matters.
Thinking about it, its probably more what the water in the ethanol fuel that does the damage.
I fixed the tecumseh that i had here.
Drained the tank and fuel bowl. Fresh fuel and it went first pull.
For some reason petrol engines do not run very well on Kerrosene. lol.
Them farmers out dads way need to try a bit harder. It takes the sport out of it.
Washed it, Cleaned the filter, re-oiled it, changed the oil and its ready to sell.