I personally would recommend changing drive unit fluid once every 4-5 years (if vehicle is used daily). This oil is not in airtight system and air moisture (with pollutants) will, over time, degrade oil. Especially in not so Californian weather. This also applies to ICE vehicle manual gearboxes, differential etc.
As of right now, Model 3 is extremely incapable in generating any meaningful amount of heat with stationary driveunit. I hope it is software based problem, but I'm not pleased with this situation (Tesla let this basic problem slip through even though removing glycol heater was conscious decision). Last winter, Model 3 owners have been stuck at SC for an hour (and even some more) as their battery was somewhat (5-10 degrees maybe?) below freezing (water freezing, not battery) until battery started to take ANY charge. This means drive unit heat production is ridiculous. I hoped for no less than 10-15kW. But it appears to be 10x less.
Can we be sure that it's just the motor (stator/rotor) that actually heats up? How about inverter electronics?
That MUST be solved before Canada/EU/Norway. Otherwise #FrozenGate