Great Thread! I'm bringing this back from a long time ago!
I have been reading A LOT on various MTF's, specifically for understanding the GL-4 vs GL-5 and yellow metal discussion (which I found more interesting the comments about carbon fiber in the brass synchros and the effect of GL-5 on that).
But, I digress. Back to Redline MTL...I ran Redline MTL in my 1991 Toyota MR2 Turbo transaxle 20 years ago (which I still have). At the time, I didn't notice any difference over the typical GL-4 MTF available in the late 90's. This transmission had about 100,000 miles on it. I was caught up in the cost of the Redline and refused to purchase it, so I settled for Royal Purple 75W90 because it was cheaper. I didn't realize it for many years (since I hardly ever drove it) that this caused some additional "notchy" "clicky-ness" shifting from 1st to 2nd gear.
Figuring the sychros were getting worn out (common in this transmission), I ended up buying a newer later model (2001) low mileage (about ~35K miles) transmission and added an OEM LSD). I maintained the Royal Purple (literally drained and used it in the new trans). I still had the same notchy shifts. About 5 years ago (and probably only 15,000 miles on the Royal Purple), I dumped it for Amsoil MTG, annoyed with the continued issue.
With the Amsoil, I still had this "clicky-ness" in that shift. It was more prevalent when cold out (Colorado), and was super annoying. I bought a low mileage parts car to rebuild some other areas of the car, and swapped in a 60K mile transmission from the parts car. I transferred the Amsoil into the new (used) trans. Still the notchy shift.
I finally broke down and rebuilt the 60K mile transmission with new synchros and I still have this notchy shift. I'm pretty good mechanically, so I can rebuild/replace stuff, but I realize I wouldn't know a bad synchro from a good synchro, unless it was REALLY bad or unless someone showed me the difference. Plus, the later model trans had an updated sychro design too. That was confusing.
Anyway, the reason I'm really interested now is...I am rebuilding a variety of Nissan Xterra/Frontier vehicles and I need to fill them all with manual trans fluid. I'm sort of back to the whole issue of $20+ per quart of fluid issue, but don't want to make another price decision. I simply want good protection and good cold weather shifts. I did analyze the kinematic viscosity and viscosity index data on about 20 different MTF's, and find an interesting relationship with the higher viscosity index (better cold temp viscosity - thinner), but was surprised the wear characteristics were good with Redline MTL (provided by MolaKule.
I did find a small company here in CO that makes a GL-4 75W90 that has kinematic viscosity characteristics similar to the Amsoil (which I really don't want) that I can buy in a 5 gallon pale, for about $6/quart. But, I just realized I can buy the same in Redline MTL for about $0.50 more per quart. It seems this should be a super simple decision, but I'm really more concerned with the fluid in the Xterra/Frontier than I am in the MR2. I want to ensure I'm getting the best product for the Nissans.
I was considering the OEM 75W-85 from Nissan, but I'll spend almost $100 for 6 quarts to get a full fill (5.3 quarts) with the OEM fluid.
Thanks again MolaKule for continuing these various conversations over the years. I appreciate your attention to these oils!
BTW - did you ever do any additional oil analysis in the Nissan Frontier to get a better idea on long term wear?