... do not know the exact way the GM OLM works, but it looks at a number of parameters,
such as fuel usage, mileage, engine temp, time and maybe some other data inputs.
So it probably flags at the 1 year mark, I know it flags on an engine overheating.
Pretty much how it works, especially resetting annually, or immediately upon an overheat, regardless of RpMs accrued -
although IMEO overheat should be 239F, 265F is way too high, especially at altitude,
and I would not use motor oil over 6 months old ... but again, IMEO ...
Just as measuring a person's health by weight is quicker and simpler, but inferior to measuring one's body fat %age,
basing oil changes on mileage is quicker and simpler, but inferior to measuring more engine operations factors.
(OLM cannot analyze oil itself, only what the engine and driver do to the oil.)
After all, two similar engines in two similar vehicles could accrue the same number of miles/km very differently -
*A racer should change their oil at less 'mileage' than Aunt Teak or Aunt Cesder accruing 40 highway miles a day ...
*Two police vehicles both accrue miles at the same rate, one spends 3x as much time idling as the other,
the one that idles less can accrue more 'mileage' between oil changes vs the idler ...
*Two 'trucks' with the same engine and axle gearing both accrue 3000 miles in 60 days,
the lightly loaded one gets 18MpG, the one that's always towing 2500lb gets 15MpG.
Should they both have their oils changed at the same mileage interval?
*Two otherwise identical engines and vehicles both average 15MpG over 60 days,
one lives in the North Pole, the other in Arizona (two different definitions of 'Cold Start'),
should they both change their oil at the same 'mileage'?
There is an ideal operating temp window, an ideal engine load window, an ideal fuel consumption window, an ideal engine speed window,
and a few other considerations.
As rules of thumb, the more time the engine spends operating inside those ideal windows,
the 'further' it can go between oil changes.
OLM also tracks the intake air temp and the coolant temp the moment before each engine start,
all of which are recorded, so even without access to 'daily time' (think older ecms / pcms),
ecm notices differences between 'summer' and 'winter' by comparing those cold starts.