I've been a fan of Redline (MTL, MT90, 75-90 (NS) gear oils etc...) for over 15 years using them in every car.
2010 Z with 19K on the ticker, I noticed how thick the OEM would get when it was < 20deg out side so I figured, time to toss some MT-85 in there.
A few days after driving with MT-85, it just was not working. I read a few reports of folks having similar feelings while others rave about how MT-85 has helped their cars.
Our car never had any issues prior: the OEM fluid worked well and there was no 1-2 issues. With the MT-85 in, the car would shift *OK* but it was off. I could tell from the first shift, wasn't the same.
The biggest thing I noticed is the synchros just didn't seem to want to engage as smoothly on downshifts, such as 5-3, or anything into 2. This was not hot lap down shifts either: SRM would put it no higher then 4000 RPM typically closer to 3200-3500. Effortless upshifts from 4-6 were met with occasional balkiness to engage. This had never happened before.
Without lab testing there is no way to compare formulations and as interesting as it is to me...I don't feel like spending $60 for new bottle samples of everything along with Blackstone tests. My suspicion is the additive package in the Nissan product just works pretty well with their syncrhos, coupled with a hypothesis that the 75/85 is on the low side where as MT-85 could be a tad more viscous. Again, no science behind that.
Today I put 3qt of genuine Nissan MTL in there and the car feels itself again. I was sad draining such nice fluid but I had to do it. Redline will continue its life in the Subaru (and I used 75/90 gear in the rear end of the Z happily) but every 30-60K looks like Nissan for the tranny in *our* Z.
YMWV
- b