SlyAsA

Or just use the petcock? Easily accessible under the first plastic shroud on the drivers side (US) of the rad, takes but a moment and only requires pliers.

bmwpowere36m3

That’ll roughly get you 5 qts out of the system another 3 if you drain the block, the remainder is likely in the heater core.

SlyAsA

Much more work though, I agree it'll get you a more complete exchange, but just using the petcock and changing every 50k takes about 10 min to get to and 30 min to do completely without the hose kerfuffle.

bmwpowere36m3

I wouldn't disconnect the hoses either... but I agree if your doing a spill and fill, then just draining the radiator via the petcock is super simple. On our car, I wanted to drain as much as possible since I was replacing the thermostat and oil cooler. The coolant was unknown, not G-48 as it had a dark amber color (maybe G-05 mixed with G-48, PO was in there). Ended up draining the radiator, block and still flushed a good 10+ gallons thru the system (multiple spill/fills).