Repair-It

Here is one data point:
https://www.msn.com/en-us/autos/ownersh ... spartanntp

I do not agree with the extrapolation that one lawn mower engine UOA means that we can change our oil change habits on cars. People already do UOAs on car oil and oil change requirements are continually validated (sometimes proving that the factory oil life monitor is recommending intervals that are too LONG), though I would have to dig to find any data on the time factor (versus the mileage factor).

I have heard of people never changing the oil on their small lawn mower engines. Keeping oil at the correct level is the most critical.

The newer and tighter the engine is, the easier it will be on oil, to a large extent - cooling is also critical. My 33 year old Briggs opposed twin is probably not a good candidate for leaving the oil in there for 65+ hours. It also has no filter, and thus no oil pump.

When I actually care about getting 500, 1000 or more hours out of a small engine, I care about oil changes. If the view is the push mower will disintegrate around the engine before the engine has an issue, you can make that argument. Lawn tractors are a bigger investment. Cars even bigger.

All engines treat oil differently, also. In that sense I would never attempt to make a sweeping generalization. But again that is more from a mileage angle.

I see no reason NOT to change oil approximately annually as a minimum though I have gone longer on my CTS-V. I worry about buildup of water in the oil with infrequent use, if the usage that DOES happen does not burn it all off (which is probably quite common).

Other than water, I actually see no particular time factor on oil life. Mileage/hours matter, however. Especially with no oil filter to collect contaminants. It should be obvious that oil does not age faster sitting in the oil pan than in the original bottle. It's all about contamination, and with more time, water would be the single biggest contaminant of concern, if it builds up faster than it is burned off.