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Re: [Fot] GL-4 question

To: jim hearn <jimhearn1@comcast.net>, Friends of Triumph <fot@autox.team.net>
Subject: Re: [Fot] GL-4 question
From: Allen Washatko <awashatko@wi.rr.com>
Date: Sat, 29 Mar 2008 19:42:27 -0500
Jim,

Moss suggests Red Line 75W90 NS for non-OD Triumph transmissions and 
Red Line MT-90 for OD applications. I have used both with positive 
results. If you read the label on the MT-90, it states that it has a 
better coefficient of friction which supports quick synchro engagement 
allowing for high speed shifting - up and down. Most gear oils and 
motor oils are too slippery for proper synchro engagement. MT-90 is 
recommended for all manual transmissions that require GL-1, GL-3 or GL- 
4 gear oils. It also meets gear oil viscosities SAE 75W, 80W and 90, or 
motor oil viscosities of  SAE 40 and 10W40. Most GL- 5 gear oils 
contain reactive sulfur which can chemically wear synchros and shorten 
their life.

Allen

On Mar 29, 2008, at 8:45 AM, jim hearn wrote:

> Randall, your piece is very helpful but would you recommend a specific
> gear oil for a TR6 tranny.  I guess my current two top contenders are
> Redline MTL and StaLube non-synthetic.  Any thoughts appreciated.  Jim
> in Sacramento
>
>
> -----Original Message-----
> From: Randall [mailto:tr3driver@ca.rr.com]
> Sent: Saturday, March 29, 2008 12:30 AM
> To: 'jim hearn'; 'Friends of Triumph'
> Subject: RE: [Fot] GL-4 question
>
>> I might have missed this but what is desirable about GL-4
>> versus GL-5, etc.
>
> Hmm, guess my previous rant didn't go through.  Too big maybe.
>
> In a nutshell, there is a sulfur additive in both GL4 and GL5 that
> breaks
> down and form sulfuric acid, which can attack the "yellow metal" used 
> in
> synchro rings, thrust washers, etc.  Conventional GL5 typically has 
> more
> of
> this additive (like twice as much), but GL4 uses it as well.
>
> However, the GL4 and GL5 standards say nothing about the additive
> itself, so
> not all GL4 and GL5 oils are created equal.  In particular, full
> synthetic
> oils typically need less of the additive to meet the performance spec;
> so
> many GL5 synthetics are considered safe for "yellow metal".
>
> There are even some oils that meet both GL4 and GL5 specs; one is
> Valvoline
> Durablend and another is Royal Purple.  It's my belief that many more
> _could_ meet GL4, but their makers just choose not to perform the tests
> or
> put the logo on the bottle.  For example, Sta-Lube used to sell a
> conventional gear oil that was advertised as meeting both specs, but
> they
> don't any more.
>
>> Does it just say that both are adequate for
>> this application but GL-5 is not no matter what brand?
>
> I believe there is a lot more to gear oil than whether it meets GL4 or
> GL5.
> In fact, I would say that the MT-1 designation is more important than
> either
> GL-4 or GL-5, for use in a manual transmission.
>
> Randall
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