can someone please let me know with certainty what REDLINE fluid (D4 ATF or D6 ATF) do I put into my 2009 328xi 6MT??? I really really need to know this. Thanks.
With certainty, it is D6 ATF, for all E90s.
I spoke with Redline's Tech Support as I was having a shifting problem and there was conflicting information on their website. However, D4 is only 10% more viscous, not much difference, and for a few situations (very hot climate, race track use) may be more appropriate.
Update: now that I've experienced a couple 100F days, D4 was the right choice for me. Shifting is perfect, and I would not want to be running any thinner than this.