E60 550i: Worth the Read

This is gonna be a long-ish read, but well worth it.

I have a 2008 550i. It's a 6MT model. Fun car.

I got it with 161k miles on it and at the time, I knew the valve stem seals were shot. Common issue. No shocker there.

I will say that they werent in the worst shape. Only smoking when i Idle for 5-10 minutes at a time, otherwise no smoke.

Fast forward:

I just had my thermostat replaced with a 90 degree celcius model, and my expansion tank replaced. Nothing else.

The car was sitting for roughly 2 weeks.

I drive my car now, and it can idle for 15 minutes and no smoke out the back at all. It's gone completely. It's wild to me.

My only thought is this, and I can be absolutely insane for thinking this, but what if the factory thermostat just causes the engine to run so hot (105 degress celcius), that it causes the factory seals to expand too much and then oil burns. With the cooler running temps, they don't expand as much, thus preventing oil from burning.

My car just turned 183k miles, and the engine has never been opened up.

My oil consumption has also come to damn near a complete halt.

I do use 5w40 Full Synthetic for those who are curious.

Do you guys think I'm insane, or am I completely missing something here?