Change coolant hot or cold?

[atikovi]

I'm just changing the coolant on my '15 Explorer P.I. that has some green (wrong) coolant in it. Drain, fill with distilled water, drive 10 minutes, repeat. Got 5 cycles done before dark and never burned myself so far. Have a few more cycles to go. Have to get it hot before the thermostat opens to get ALL the old coolant out.

 

[mightymousetech]

Maybe 300* on track day. Around town, about the same as coolant or less under low stress.
I think he was referring to the danger of opening a pressurized cooling system.

I change my coolant and oil at the temp I like my beer..........cold.

BMWs run colder when driven hard than when steady highway cruising. Just sayin’

 

[Zaedock]

BMWs run colder when driven hard than when steady highway cruising. Just sayin’

Steady highway cruising is the easiest condition an engine will see. You'll have to post some pics of that BMW anomaly.

Here is a post from an E90 forum comparing track vs "cruise" oil temps.

 

[mightymousetech]

Steady highway cruising is the easiest condition an engine will see. You'll have to post some pics of that BMW anomaly.

Here is a post from an E90 forum comparing track vs "cruise" oil temps.

View attachment 73666

That’s oil temps, not coolant. BMW have “map thermostats” controlled by the DME that lower thermostat opening temps when driven aggressively. Highest coolant temps are reached when driving at steady state for best FE.

 

[Zaedock]

That’s oil temps, not coolant.

Correct, because I was talking about oil temps.

 

[mightymousetech]

Correct, because I was talking about oil temps.

Sorry, I missed that.