Miata Turbo Forum - Boost cars, acquire cats. - Just bought some Redline 75W90

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Just bought some Redline 75W90 - OK to use in Trans?

Hey guys,

I just bought a couple bottles of the Redline 75W90 oil. (was on sale)

I just want to make sure that this stuff is OK to use in the tranny, as it seems like the website is saying it is more for Diff use.

Is anyone using this stuff in their trans or should I buy some 75W90Ns instead?

Thanks

Isn't that just gear oil...?

Because they have MT90 and MTL for the trans.

its good for the rear end, use mt90 or motull 300 in the trans.

I just bought some MT90 this weekend and on the back of the bottle it says "75w90".

It seems to me the 75w90 and the MT90 are pretty much the same thing.

Call Redline and ask them.

Red Line Oil: Gear Lubricants

Quote:

MTL is a low 70W at very low temperatures and a high 80W, nearly an 85W, at elevated temperatures, providing adequate viscosity to prevent wear and deaden gear noise. MT-90 is a thicker 75W90 version of MTL.

Quote:

75W90 NS

This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin.

mt90 and their 75-90 are different formulas.

I just put 75w90NS in the clutch type a few days ago. Can't recommend it at all for a daily driven car. It pops and snaps something fierce when the fluid is warm.

I'll throw my.02 in here as I have used all of the RedLine diff/trans fluids they offer. If you are running the OE 5 speed and you shock load the trans from time to time, I would RX using the Heavyweight Shockproof fluid (actually I don't know why the call it fluid, it's more like coagulated blood in color and consistency) in the trans. You will have a little notchier shifting when the outside temp is below 50 degrees, but once it warms up, shift effort will reduce to MT90 levels. The only issue with the Heavyweight Shockproof is you will need to change fluid about every 8 to 12 thousand miles depending on how you drive. The buffers suspended in the fluid compress over time and reduce its effectiveness. It also has more parasitic drag which means less HP to the wheels (about 1-2 per 100 HP over a conventional 75-90 fluid). If you are running a turbo/SC, it won't be a problem.

If you don't normally shock load the trans then the MT90 would be the best option. If you live in a cold climate (below 50 degrees @ the warmest time of the day), then the MTL would get the nod.

75w90 from redline is the wrong stuff for the tranny... it will shift like ass.

even the NS kinda sucks in a miata tranny.

and sav: try adding some friction modifier to your diff. I think you want ford type. probably available at FLAPS