[SaltyNC]

I can't offer any firsthand experience with longterm use, yet, but I researched this a lot. I don't know that I ever saw a negative comment regarding Royal Purple Synchromax. I think I saw one neutral comment that it was no better than stock, but never a negative comment. The majority said RP was excellent and offered better shifting characteristics over stock. It was what I had planned to use in my transmission. My Z4MR had original fluid at 30K, and my transmission was notchy and sometimes denied a 3rd to 4th shift at lower RPMs.

I now have Redline D4 in my trans. Just replaced. It's what my mechanic prefers. It is smooth right now, but I also did other work (VT engine mounts, Rogue trans mounts, CDV delete, and I have a weighted shift knob). It is like a different car, now. I know a lot of folks run Redline MTL and some a 50/50 split of Redline D4 and MTL. MTL is thicker. So, I'll report back when I've put 10-15K on this Redline D4. A few anecdotal stories are that Redline is excellent at first but shifting isn't as good after it has substantial miles on it. I may try RP in 15K miles if the Redline D4 degrades just to see if I can tell a difference.

Salty