Power Steering Fluid - CHF11S to ATF

[prostcfc]

I'm going to switch to ATF. It is said not to mix, but I found this nugget (https://www.bimmerfest.com/threads/w...3868/?u=268063) which includes a service bulletin stating:

"CHF and ATF oils must not be mixed. The oil types are indeed compatible, but if there is more of the one type in the steering gear then the other, this adversely affects the properties of the other oil."

So if there is a little CHF stuck in the steering rack (I've read it can be a bit difficult to get everything out), seems like that isn't the end of the world.

[bigjae46]

Do you have to blow out the PS lines and rack when switching from CHF11 to ATF and vice versa? I'm thinking about changing my E90M3 to ATF.

[Slideways]

Do you have to blow out the PS lines and rack when switching from CHF11 to ATF and vice versa? I'm thinking about changing my E90M3 to ATF.

Depending on how much ATF you have on hand, my guess would be to drain the CHF, fill with ATF, run the engine for a few minutes, drain the ATF, refill, drive for a few 100 miles, drain and refill again. Castrol Dextron IV is ~$45 for a pack of six.

[bigjae46]

Depending on how much ATF you have on hand, my guess would be to drain the CHF, fill with ATF, run the engine for a few minutes, drain the ATF, refill, drive for a few 100 miles, drain and refill again. Castrol Dextron IV is ~$45 for a pack of six.

So not an instantly deadly sin to mix a little but do want to flush and couple of times. I can do that…I think

[Slideways]

So not an instantly deadly sin to mix a little but do want to flush and couple of times. I can do that…I think

I mean, if you want to get really crazy, it is probably a good time to change out the reservoir on the final refill since the reservoir has a filter in it.

I have a feeling most track guys would just dump the CHF, refill with ATF and call it a day

[BTB]

I don't know what the reason was, but the e9X M's suffer from power steering feeling boiling on track even in noob group.

Can confirm … on a wet October day in Wisconsin (Road America)