On August 25, Andy Mace wrote:
> Gearbox and differential oil don't need to be changed at all -- only
> topped up as needed.
Andy, I'm not challenging in any way what you have written and I know this
is what the factory recommended in days of yore. However, I have long been
of the opinion that this was a shortcut on Triumph's part to reduce owner
servicing costs - and I'm not too convinced whether it was really the right
way
to go about things.
When I last removed the diff plugs on my cars to check oil levels, I stuck
my finger in the holes and took a sniff at the oil sticking to my digit. In
layman's terms, it reminded me that possibly a herd of tomcats had been in
there for far too long - and any oily aroma had long since gone.
Over the years, I've speculated on how long an oil can reasonably be
expected to last and still do the job. I know nothing at all about the
chemistry of the oil industry but I know things called polymers are present
in oils which presumably are there to protect and keep the oil in good
order. What happens to these polymers through the undoubted shearing action
they must encounter as the diff or gearbox is working? The tooth loading on
a crown wheel and pinion must surely be many tons per square whatever and
how long can an oil REALLY last? I have to say I've never subscribed to
this 'lifetime' oil claim and I've changed the oil (with difficulty) on a
number of occasions because I don't see how it can be expected to go on for
ever. Does anyone want to comment and allay my concerns?
John Mac
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