I don't think we really have to worry about what oil we run in our small engines.. The other day, I did an experiment. I picked up a 20 year old mower with a rusted out deck, destroyed handle (bend, broken, wheel missing) (A briggs 3HP Classic) that had never had the oil changed for $5 and took it out to the country, far from anybody. the guy just bought a fancy new Honda and sold it to me (wasn't even worth the $5 really. Anyway, I drained the oil (Very little, blacker than sin) and filled it with bar & Chain lube. Ran it for a little bit, it ran fine. Next step, get some dirt amd dump it in the crankcase. Started it up. Ran. Knocked slightly, but still ran. Smokes a bit. Baffled, I Dump more in. It knocks loudly for a few seconds, and idles down, clacking slightly. I shake my head. removed air filter cover, I rev it up a good bit, nothing. I take some dirt, and with the throttle mostly open, I pour dirt down into the carb intake. It chugs down and starts smoking a bit more. I let it run, it keeps going.
Unbelieving, I repeat both dirt in crankcase and dirt down intake. Not even smoking very much. A good deal harder to start. On starting, it knocks very heavily for about 10 seconds, then smooths out and knocks lowly.The dirt having stiffened the throttle plate bearings, I jam it wide open and let it run for 5 minutes. Nothing spectacular. No real knocking, barely smoking. I cannot believe it. I gave for the day. I am determined to kill this thing., and will resume sometime soon. For what it's worth, the throttle has to be wide open and it is difficult to get it to start now, and I find oil being blown out the bottom of the muffler, and settling on the deck. I am assuming that the seals in the valve spring chamber are failed.
But I don't believe it. We could probably run 50 year old 80W-90 and it would chug away happily for years.
P.S. - Don't tell Al Gore...
Unbelieving, I repeat both dirt in crankcase and dirt down intake. Not even smoking very much. A good deal harder to start. On starting, it knocks very heavily for about 10 seconds, then smooths out and knocks lowly.The dirt having stiffened the throttle plate bearings, I jam it wide open and let it run for 5 minutes. Nothing spectacular. No real knocking, barely smoking. I cannot believe it. I gave for the day. I am determined to kill this thing., and will resume sometime soon. For what it's worth, the throttle has to be wide open and it is difficult to get it to start now, and I find oil being blown out the bottom of the muffler, and settling on the deck. I am assuming that the seals in the valve spring chamber are failed.
But I don't believe it. We could probably run 50 year old 80W-90 and it would chug away happily for years.
P.S. - Don't tell Al Gore...
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