> 1. The shop manual says use 90W gear oil. Is this the same as
> what goes in the transmission?
That's one of those perennial debates ... but the TR6 owner's manual says to
use gear oil in the transmission and the trunnions.
> If so, does it have to be GL4 since the trunnions are yellow metal.
IMO it doesn't matter in the trunnions, since they don't get hot. But then,
I still have never heard of a case of GL5 harming a Triumph transmission
beyond turning the brass dark ... I suspect that the dire warnings against
GL5 are, at best, misguided. Especially since most GL5 oil also meets GL4
specifications !
But, I haven't yet tried oil in trunnions, since TR3 trunnions are supposed
to be greased. When I do oil the trunnions in my Sports 6, I'll be using a
"copper safe" marine gear oil (GL4 equivalent) only because that's what fits
the oil gun I bought.
> 2. Why are these things oiled rather than greased?
There are several possible reasons ... take your pick :
1) The factory said to use gear oil.
Why did they say that ? Don't know for sure, here are two theories :
2) Gear oil doesn't dry out the way old British grease did.
3) Gear oil has a recirculating effect that helps flush wear particles away
from the contact surfaces, resulting in longer life.
Randall
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