Jon;
I agree wholeheartedly with you on regular drain and refill intervals of both
the gear box and differential. 80w90 is tough stuff, but it doesn't last
forever. I get questions about this all the time and I answer in the most
truthful way I know, but I still get the impression that a lot of customers
(who don't do their own maintenence) just think I'm out to get a little bit
more of their money. A case in point, one of my customers just got a new
Porsche Boxter. Now, jaded that I am , I think its a real nice car. The
factory recommended oil drain interval is 15,000 miles using Mobil 1 synthetic.
Guy asks, should I do this? I told him, I can't imagine you're doing your
$41,000 car any favors by waiting 15k miles before changing your oil. Am I
wrong and the factory could somehow be right? I don't think so. Oil changes are
cheap and easy. The damage done by being pigheaded can be very expensive
indeed.
Just my $.02
Jeff Johnson
jonmac wrote:
> 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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