<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="Generator" content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style></head><body lang="EN-CA" link="#0563C1" vlink="#954F72" style="word-wrap:break-word"><div class="WordSection1"><p class="MsoNormal">On Fri, 29 Jan 2021 Sujit Roy <a href="mailto:triumphstag@gmail.com">triumphstag@gmail.com</a> asked:</p><p class="MsoNormal"> </p><p class="MsoNormal">>Anything against putting this stuff in my diff. I have in my manual gearbox in my Stag</p><p class="MsoNormal"> </p><p class="MsoNormal">I looked into this when trying to find an appropriate fluif for my TR3A’s differential. I don’t know how relevant this would be to your Stag, but I’ll offer it up anyway.</p><p class="MsoNormal"> </p><p class="MsoNormal">The contributors to his list showed a preference for: </p><p class="MsoNormal">- Redline GL-5 75W90, or</p><p class="MsoNormal">- Royal Purple Synchromax 75W90, or</p><p class="MsoNormal">- Kendall Gear Oil, 75W</p><p class="MsoNormal"> </p><p class="MsoNormal">With that in mine, I contacted Red Line Oil, the makers of MT90. They replied that “The TR3A differential originally called for an SAE 90 GL-4 and the MT-90 would be recommended”. When I asked about the caution on their web site that “MT-90 are not for use in differentials with hypoid gears”, Red Line responded that “The note on our GL-4 gear oils refers to use in a high offset hypoid application which your Triumph doesn’t contain. The GL-4 gear oils are suitable in zero and low offset ring and pinion applications.” </p><p class="MsoNormal"> </p><p class="MsoNormal">The late (and much missed) Randall Young advised that “MT90 has friction additives” and felt that one would want friction in a transmission but not in a differential.</p><p class="MsoNormal"> </p><p class="MsoNormal">When I asked Red Line about the friction additives, they replied that “If you wanted a more slippery product one of our GL-5 gear oils such as the 75W90 or 75W110 would be options, they contain a friction modifier and are compatible with phosphor-bronze as they contain a copper deactivator”. Red Line summed up by saying “In your differential technically either could be used, the 75W90 contains a friction modifier beneficial overall for friction and temperature reduction.”</p><p class="MsoNormal"> </p><p class="MsoNormal">As a result of that investigation, I’m using Redline GL-5 75W90 in my TR3A’s differential. I use the MT90 in the gearbox. I’ve had no issues and noticed no ill effects when I examined the diff during a rebuild last year.</p><p class="MsoNormal"> </p><p class="MsoNormal">However, the Red Line oils are hard to come by where I live, and are quite expensive (about $25/litre). Some of the other TR3 owners locally have been using Sta-Lube GL4 85W90 Gear Oil which is about half the price of the Red Line products and is readily available from NAPA.</p><p class="MsoNormal"><span lang="EN-US" style="font-family:"Verdana",sans-serif;color:#2f5496"> </span></p><p class="MsoNormal">Regards,</p><p class="MsoNormal"> </p><p class="MsoNormal">Dave MacKay</p><p class="MsoNormal">1960 Triumph TR3A, s/n 68639L</p><p class="MsoNormal">near Toronto, Canada</p></div></body></html>