On Thu, 15 Apr 1999, wood wrote:
As my knowledge of Things Oily is limited, I'm forwarding this to the
Triumphs-list in the hopes it will generate some better responses....
> In reading the Haynes shop manual under routine maintenance, I read " it is
>not recommended that the oil be drained except at overhaul periods as the
>gearbox and overdrive unit (if fitted) are filled with a special oil at the
>factory when new".
>
> Our resident Triumph TR4 mechanic suggests that changing the oil in the
>gearbox usually leads to problems. He advises to top off the level rather then
>change it. I suppose without the "Special" oil using Hypoid oil SAE 90 has
>presented some problems.
Hmm. I'm not so sure about that. I had to change the oil in my
automatic-betransmissioned econobox; the old oil was black (not burnt),
and the filter was full of little twinkly bits (= metal swarf). I think
that changing the fluids, especially when hot, should do some good for a
transmission.
I wish I could recommend the proper replacement fluid with confidence, but
I can't. There still is a lot of mystery surrounding just what should be
put into the gearbox- I surmise that most any heavy-weight oil will work
(90w gear oil, GL4, GL5, 30 or 40W motor oil, etc) but I make NO
guarantees.
> Question 1: What special oil are they referring to?
I don't know. I suspect that Haynes didn't know either; often they would
copy text straight out of the factory workshop manual. And they probably
didn't tell either :-)
Anyone out there know the answer? What made the oil so Special?
> Question 2: If I use the synthetic oil GL-4 or GL-5 recommended, will this be
>compatible with the Hypoy oil that was in the gearbox originally. Do I have to
>be concerned with flushing the gearbox and if so what do I use to effect this.
To my knowledge, oil is oil, and therefore (as they're both petroleum
solvents) will mix with each other quite nicely. I could be wrong (can
oil curdle??)
I topped up my diff in my TR4 with GL5 (Castrol Hypoy, non-synthetic). It
hasn't exploded yet. I intend to do the same with my transmission when I
can get the stupid plug out.
-Malcolm
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