What oil temps does it run vs ambient? That's a big factor in oil life. The Briggs 25hp PXi on my ztr is running 175f oil temp in 90f ambient. That's a sweet spot for oil life as far as I'm concerned.
On the GM version there's a step in the CDF bushing bore that prevents the "bushing walk" problem that Ford had in their early versions. Not sure how many other subtle differences there are.
New York City Sanitation was considered one of the toughest fleet locations by Allison. They also put snowplows on the trash trucks in winter. Although this was based on transmissions rather than engines.
There are successful designs that use this approach including a lot of half million mile rated Allisons. It comes down to the specific loads and the processing of the mating parts. On this one they missed some design details. Surely their validation test units were showing this as an area of...
Running out of oil has killed many engines. Running an incorrect or substandard oil very few. But since everyone on here checks their dipstick daily, and effectively never runs out of oil, specs are the only thing left to discuss.
It's really the oil temp that counts. I mowed for an hour in 90F and the engine oil in my Briggs was 170F. There's nothing in the physics that makes me think the oil temp wouldn't increase pretty linearly with the ambient.
The important question is - what is the engine oil temp when that happens. It may be a lot lower than you think.
I see more Exmarks doing commercial mowing than any other brand. I assume they have satisfied owners and the word gets around. (I bought a Ferris because of the suspension system).
Old mower in storage but had been stored dry carb and tank. Filled it up, no start.
Checked spark, nada.
Plug wire seriously chomped on. Infinite ohms.
Went deluxe and got new $10 magneto on Amazon.
Started right up.
Factory assembly people shun oil/grease on the line whenever possible. Added time plus housekeeping headaches.
Sealed suspension joints, unitized wheel bearings, prefilled transmissions with quick connect fittings.