[TR] gearbox oil

[Randall]

> Hi: What is the correct gearbox oil to use. In"How to restore a Triumph"
> byRoger Williams He say to use ST90 gear oil. But in the TR3 Service
> instruction Manual it says to use SAE 30.  Thanks Larry

As you may have gathered, Larry, this is an often-debated topic with no
clear answer.  It's actually much more complicated than it seems, since
there are lots of variations in both "gear oil" and "SAE 30".  Even
Standard-Triumph changed their recommendation several times (after the
Service Instruction Manual was printed).

Likely, if you drive conservatively, it doesn't actually matter much.
Either one will do.  The issues seem to arise when you start driving hard
(as I like to do).

But rather than going through the whole host of reasons why again, I'll just
say that my recommendation would be either Valvoline 20W50 "Racing" oil
(which has been extensively tested by some folks who live in hot climates
and drive their Triumphs hard, but was likely reformulated since then); or
Redline MT-90.

If you do opt for another "gear oil", IMO it's important that it be rated
for "MT-1" service (which you will not find mentioned in any Triumph manual)
and at least GL-4.  (IMO GL-5 is acceptable if it is also rated MT-1, but
not everyone agrees with that.)

Randall