How come they've moved away from the usual 10w30 they've required for years?

Not true.
The fact is that you have it backwards, and even many engines that have an oil filter use splash lubrication.
How does a splash style system create flow for the “oil pump” or whatever it is that would cause the oil to flow through the filter?
 
with the exception of your basic el cheapo box store 6hp lawn mower engine, most every other air cooled engine is full pressure lubricated with an oil filter. Not any different than a car.
None of my OPE has a oil filter, but they are all B&S or similar, or 2 stroke. Even my 3000W yamaha generator has no filter, and I assume its got a pressurized oil system, but you just change the oil.
My kingquad 300 has a little filter, but the CRF100F just has a screen somewhere in there, and the CRF gets its new litre of oil every 10-15hrs.
 
I always thought you weren't supposed to use oils with a big gap between numbers because the 10w50 will just shear down to a thinner oil over time. Maybe oils are better now and it's not a problem now
Not quite sure if that's a rule. If so, it will probably have all the "thickies" on BITOG up in arms.
 
Not quite sure if that's a rule. If so, it will probably have all the "thickies" on BITOG up in arms.
It will shear down to the smaller number is what I meant. I've been on here for years, so that's just my understanding. Unless motor oil has improved over the years and they have figured out a way to overcome the shearing.
 
It will shear down to the smaller number is what I meant. I've been on here for years, so that's just my understanding. Unless motor oil has improved over the years and they have figured out a way to overcome the shearing.
Some VM (vi) are better than other but, that goo ain't oil and all-season multigrade oil has been and still IS a big compromise.
Best to not expose yourself to it if you can help it, especially in Hot weather ODPE aircooled applications.
 
It will shear down to the smaller number is what I meant. I've been on here for years, so that's just my understanding. Unless motor oil has improved over the years and they have figured out a way to overcome the shearing.
Well I wasn't going to use that Kohler command 10w50 for $17.99/qt
 
How does a splash style system create flow for the “oil pump” or whatever it is that would cause the oil to flow through the filter?
They have a very small oil pump, and are actually very simple devices. It sits at the bottom of the sump, the shaft is keyed to the camshaft, to a small rotor inside a housing. Really not much to them. Some systems deliver pressurized oil to the rod and crank bearings, others dont do much more than route the oil through the filter, and splash does the rest. Really depends on the engine and who built it.
pump.webp
 
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