Question about Lube…

I just replaced the clutch on my 2009 Miki Cooper S, and used Redline MTL that I had from another project to refill gearbox. 

When I looked up the Mini on the redline site, the MTL (75w80 GL-4) was what was recommended, which was great since I had 3 unopened quarts sitting in my shed.

I noticed there was a sticker on the gearbox saying it was filled with MTF-LT-4. From what I can find online the MTF-LT-4 is 75w90.

Being in New England, is the Redline MTL going to cause any problems (short or long term)?  I'm not expecting it to, but figured it was better to ask now, than have something fail in the future.

The only thing a guy would notice, short term, is if the oil is too slick for the synchros.

I've found, over the years, if it crunches into second gear, keep putting lighter oil in until it shifts properly.😀  I ran an old Jeep Commanche for many years on atf...of course, the 2.5 had about 65 pound feet of torque.

In reply to Streetwiseguy :

Thanks. I figured it would be fine, but wanted a second opinion.  

The shifting is fine, and no noise when shifting up or down through the gears, regardless of rpm. 

The MT-85 would probably be a closer fit for yuou should be ok either way if you're doing regular changes.

The old hotrod setup for bad DSM transmissions was to take out the gear oil and run GM Synchromesh.  I dont know what was in it, it sure was thin, but holy smokes did it shift nice after that.  

I think you would be fine, Redline is a premium oil, I wouldnt worry about the weight unless you were really tracking it hard for extended periods at high temps and high load.  

If we're talking fluids for other transmissions I've been very happy with Ford MOTORCRAFT Full Synthetic Manual Transmission Fluid XT-M5-QS in my Getreg 260/6 (with over 400,000 km on it) in the E28. It's about a 75W90 but shifts well from cold to hot, there's some clatter with the clutch out in neutral but not nearly as bad as with a thinner fluid in there. I can't say I've ever been impressed with Redline in my cars, it would work fine warm but until it got there the synchros were not happy. The Ford stuff is easy to buy through any of their dealers and affordable.

My E90 specifies an MTF-LT-2 (for the lifetime of the trans!), I recently put Royal Purple Syncromax in it as it about the same viscosity as the BMW fluid that came it. I can report it is shifting quite nicely with 340,000 km on it. Syncrhomax in the above Getreg 260 shifted well but with the lower viscosity made a racket in neutral.