[Mergatroyd]

Rear main seal leak that persists. 1998 Camry 2.2 with unknown engine miles-- suspected to be quite a lot of miles. Seal has been replaced twice during my ownership-- not low cost to do so. Repair lasts less than 8000 miles the first time and less than 5000 miles the most recent time. I suspect excessive engine blowby resulting in high crankcase pressure could be the problem. Oil consumption is not excessive nor is visible exhaust smoke. Engine power is normal as is fuel mileage.
PCV valve will be changed this week. No "Check Engine" light showing. Will not spend to replace the seal again.
Any ideas about this?

 

[Cosmofennema]

Oil control rings losing their ability to seal, leading to blowby as you suspect.
These engine's rear main seals are robust, so it's something else that is likely making them go bad.
Damage to the crank sealing surface may also be the culprit.