Originally Posted By: boraticus
From what I've seen over the years, lawnmower engines can run forever on most any form of lubrication. The kid next door at camp was given an ancient Toro and he brought out to cut the grass. He hit a stump or something and stalled it. It wouldn't start after that so we tipped it on it's side to look things over and black ooze started spilling out of the crank case ventilation tube. I told the kid to check the oil. What oil? I bet that machine was running on less than four oz. of tar like grease and it was running pretty good. Smoked a bit on start up but ran clean
thereafter.
We put far too much effort into analyzing what would be the best oil for lawnmowers. Any engine oil will do the job and I doubt very much that the type or brand will have any influence on it's longevity. The machine will likely fall apart before the engine fails provided it has some form of oil in it.
In other words, don't bother buying the overpriced lawn mower engine oil. Car oil will do just fine.