the oil life monitor decreases in percentage substantially slower during lengthy cross-country roadtrips.
The Oil Life Monitor subtracts miles from 'an account'. When it runs out of miles, time for another oil change.
HOWEVER
some miles 'count' moreso than others.
There's an ideal engine coolant temp range
an ideal engine RpM range
an ideal engine load range - although the proxy for this is time spent with the TCC locked in an overdriven gear.
Miles accrued inside those ideals count the least.
That's why cross-country trips extend the Oil Life Monitor's mileage.
The more miles accrued
while the engine is cold
at higher RpM
in 1st 2nd or 3rd gear with the TCC UNlocked
the more often the Oil Life Monitor will suggest changing the oil.
And yet, in spite of all of the above ...