Most 4 strokes oil by a slinger driven off from the crankshaft, they sling more oil @3600 rpm's than they do at less throttle. A lot of lawnmowers have no throttle any more because of this. If it has an oil filter disregard, as they have a pump.
Man thanks for the heads up about country line log splitters bought from tractor supply. Pulled the wheels to check the bearings as some complaints have been leveled on the web, sure enough no grease!! Good thing I only went 8 miles. Doesn't make me very happy but if I drove 20-50 miles, would have been broken down.
Must be another reason why we men are designed to stand up when we gotta pee. All the more reason to do it that way. I still split horizontal but Its because I can still lift my damm pig rounds!
Going back to engine speed, I don't run an engine any faster than it needs to run to do a good job...never had one blow up from lack of lubrication. If you think about it, running at 3600 RPM may move more oil, but more oil is then needed too. Some quick and dirty "back of a napkin" math reveals an average small engine oil slinger traveling at ~10MPH at idle speed...I think 10 MPH is adequate to splash plenty of oil...and like I said, that's at idle speed...I know traveling down a muddy lane with a clean truck at 10 MPH sure splashes plenty of mud! I've always figured the old tale of "gotta run at WOT to lube properly" was just that, an old tale....woulda said an old wives tale, but I don't think too many wives sit around discussing this stuff...
There's still compression in an engine but considering that any lawnmower is running, Ive never adjusted the speed on a push mower. Ive never doubted the oil on a 4 stroke as long as I check it. But basically the pressures are only so much in a small engine that its hardly worth mentioning or comparing to your average car. Even the sump pumps in cars aren't that much as far as pressure goes but within any engine level designed to do what it's supposed to do, its hard finding an engine that hasn't been tested to make sure the internal parts function at the rates it needs at optimal operational speeds. There's a reason why they count on timing but the best thing is to always make sure you have enough oil in the dang thing or you're gonna have an unhappy wallet.