Let's talk oil temperatures on the street

226° coolant temps aren't really anything to worry about if you're using coolant and your system pressurizes just fine.

Given that it's a BMW though, it will blow out the radiator tanks or other plastic parts at some point.

Cactus wrote: 226° coolant temps aren't really anything to worry about if you're using coolant and your system pressurizes just fine. Given that it's a BMW though, it will blow out the radiator tanks or other plastic parts at some point.

Yeah, in theory it shouldn't be an issue, but since it's a BMW all the plastic bits fail one by one. I had to replace my radiator shortly after buying it. The bad thing about the system being pressurized is that the most minor leak can become quite violent in no time at all.

Pretty much any plastic in a cooling system has a limited lifespan. It'll only survive so many heat and pressure cycles before wearing out. Running it a little cooler may make the bits last a little longer, but I doubt it would be a big difference.

Better to just run the temp in the engine's happy range and plan the lifespan of ancillary parts based on that.

rslifkin wrote: Pretty much any plastic in a cooling system has a limited lifespan. It'll only survive so many heat and pressure cycles before wearing out. Running it a little cooler may make the bits last a little longer, but I doubt it would be a big difference. Better to just run the temp in the engine's happy range and plan the lifespan of ancillary parts based on that.

Yeah, I'm not complaining too much since the cooling system parts are relatively cheap and easy to install. However, I did notice that the E39 M5 (which has a slightly bigger engine) runs a lot cooler at 95ºC (203ºF) and its cooling system lasts at least twice as long as on a 540i, despite using extremely similar components.