Miata Mailing List: November 1997, Message #190
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From: 	David Okamoto <davo@lsil.com>

Subject: Re: 

Date: 	Sun, 2 Nov 1997 19:08:50 +0000



EScheidl@aol.com wrote:

> 

>  of mention referring to the use of Red Line MTL in the

> transmission to improve shifting ease and tranny longevity, but I never see

> anyone refer to the use of Red Line MT-90.  I have been researching Red

> Line's product line since my 93 has 40k on it and I want to switch to a

> synthetic gear oil.  It appears to me from my research that the product of

> choice would be the MT-90.  The MT-90 is a 75W90 GL-4 gear oil whereas the

> MTL is a 75W80 GL-4 gear oil.  My owners manual says to use 75W90 GL-4, GL-5

> gear oil, and in temps. above 50 deg. F (10 deg. C) to use 80W90.  The

> literature that Red Line sent me says that the MT-90 "uses the same chemistry

> as MTL, but is a 90 WT in order to satisfy certain manufacturers which

> recommend SAE 90 GL-4 gear oils".  Is it just that the MT-90 is a new product

> and nobody has had a chance to try it yet?  Or is the MTL really better

> suited to the Miata's transmission.  Any comments will be greatly

> appreciated.

> 

> Thanks;

> 

> Ernie Scheidl

> 93 Base Classic Red (Hard Top on for the Winter) :-(

> Drain, OR



Ernie:



With 5,000 miles on my odometer 2 years ago, I put MT90 in my trans to

see if it would smooth the shifts somewhat.  I decided on MT90 for the

same reasons that you expressed.  I even called Redline and they said to

use the weight the owner's manual recommended (probably to avoid any

liability issues by recommending anything else), which is equivalent to

MT90.  I noticed no difference in the shifting.  After a couple of

months, for $15.00 and a little effort, I thought I'd try the MTL. 

After filling with MTL, the shifting got smoother with each shift,

especially the 1 - 2 shift, which is characteristically a little balky

(at least in my trans).  The cold shifting problem is now gone and every

shift is as smooth as a hot knife through butter.  I have a C's short

shifer in mine which increased the shift effort a little due to the

higher fulcrum point on the shifter and the MTL has done wonders to ease

that effort as well.



I don't know if Mazda would honor a warranty claim for a transmission

problem if you're using MTL (lighter viscosity), but I recommend it

highly, just based on my own experience.



Dave

-- 

Dave Okamoto

LSI Logic Corporation

mailto:davo@lsil.com