So so true! Awesome.

I think this is more to do with the year and era of when these plastic end tanks were made, these modern cars have better manufacturing processes and quality control on those plastic parts than the plastic parts of old.

I know e36s m3s and other bmws from the 90s-00s had major issues with the plastic end-tanks cracking. On our cars however it isn't an issue.

I have that "issue" but it's more prevalent during the summer, and I've had a gallon of subaru oem coolant in my garage since 2016 that I used to top off the system and it's not even close to empty. It doesn't really lose alot of fluid, almost a 1/4-1/2 an inch of fluid in our 5 month hot summer period.

Apparently someone said the fix is that there's evaporation occurring through the OEM hoses and through the top cap of the expansion tank. So putting tape over the expansion tank cap and swapping the hoses to aftermarket with hose clamps seems to do better. But it's honestly a non issue for me as it isn't a crazy loss.

By the time I did my coolant change I had used almost a whole gallon of coolant to refill the overflow. I think this time around I'm just going to use water to top it off.

BMWs have been running 2.0bar/29psi cooking systems since the 90’s with plastic radiator end caps, and they rarely, if ever, failed. The pressurized coolant reservoirs aka expansion tanks (with much greater effective diameter and hoop stresses) were a whole different story.