Originally Posted By: wapacz
I put 5w20 in mine. I figure that oil really never really gets up to a sustained 100c. When there is snow on the ground.
But, you should also count on the fact that if that is true, the people who designed the engine also know that and yet specified what they did.
I contend that snowthrowers are the hardest working OPE out there, at least in any locales that see wet, heavy snow and salty end-of-driveway mounds from the plow. People want to get their driveways cleared as quickly as possible and ram these things into the snow until they almost stall with the throttle wide open. I don't see this much from lawn mowers, power washers, line trimmers, blowers, generators, water pumps etc... many of which have "designed" loads (pumps can only pump so fast, generators have a maximum output) which only load the attached engine to, say, 70-80%.
I want as heavy protection in there as I can get which isn't "too thick" at startup. GC is almost a 40 weight @100C and has high HTHS but still earns a 0W cold rating. I think this would work well even in very cold climates. In my specific climate, it's usually "warmer" if there's snow heavy enough for the thrower so I could probably even get away with a syn 5W40.
I've read that Tecumseh's are more sensitive to oil level than the competition and have been severely damaged by being "a little low" or spending too much time tipping back riding up into snowbanks or EOD.
At any rate, in a nutshell, I wouldn't recommend that the general public go thinner than the manual says for the above reasons. You may not notice effects right away, but I wouldn't take the chance. I certainly wouldn't feel that I was doing the machine a "favour" by going lighter, especially in a Tec.
