I don't know if I've followed this thread thoroughly... but my reason for
changing the diff and trans oil has little to do with whether the oil is still
good... There's no filter in these units... While there is supposedly an oil to
oil contact on the gears... I assume there is some wear, here and there... and
this wear produces metal particulate matter... and there's oxidation/rust
matter
that sometimes forms on a gear when a car has sat for a while... only to be worn
away when run... and I'd like to keep that stuff out of there... I'd rather
not
slush my gears with dirty oil.
I would not wait 50,000 miles to change the oil... I think it's cheap insurance
to change it a tad more regularly... I'll probably change mine soon... which
would put it at about 15,000 miles.
It's not like the oil is all that expensive... and it's good to see how the oil
looks... as part of your car's yearly or regular physical... :)
I have always considered oil to be a car's life blood... I change it regularly.
Even if I bought some modern car that said I could run the motor oil for 100,000
miles w/o a change... I would still change it at about 15,000 miles.
Those that would condemn me for ecological reasons... remember, the oil is
recycled. And if there's waste here, it's a very small thing in the big picture
of petroleum product waste in this country. And I could argue, that my cars may
last longer and burn cleaner because of such efforts... hence... creating less
polution and waste in other areas. i.e. how much polution is created to make a
replacement motor or car! blah blah blah... any flames in this area,
regarding
my oil change habits, are going to roll off by back...
I recall taking my motorcycle in for work at a shop... (when I had one) and they
asked me when it had been rebuilt. I said it had never been rebuilt... they
were amazed... they said the motor was so clean inside, they thought it had to
have been rebuilt... and there wasn't the sort of wear on the lifters that they
expected to find... etc... This is from, in my opinion, my oil changing
habits. And when I have broken down my Truimph motors... I always find them as
clean inside as when I first put the motor together.
my 2 cents.
--Justin
Cliff Hansen wrote:
> John and Andy,
>
> In my experience (not backed by any polymer chemistry),
> we should change the gearbox and diff oils. However,
> not more frequently than every 3 to 5 years or 50000 miles. This is for
> standard gear oil in normal driving, I don't know about the synthetics or
> about cars used heavily (racing, autocross, etc.) When the
> distinctive sulfur-like smell fades to a sour or burned smell, its time to
> change the stuff.
>
> I worked at a Jiffylube-like place to pay for college and I've drained
> 30 year old gear oil. Believe me you don't want that stuff in your car.
> It looks and feels like its reverted to its original form (crude oil.)
>
> Since its a real bear of a job to drain the diff (and to refill the tranny),
> call around to the local lube shops and ask if they have a vacuum
> tank that removes the gear oil. Basicly it sucks the oil out of a probuscis
> (word of the day) that you stick in through the filler plug. Most shops also
> have a pump to refill and can do the tranny lots easier than the average
> owner. For me it was worth the $20 I spent to have the lube shop
> do these jobs.
>
> Be sure to warm up the oil by driving around for an hour or so first,
> which of course is the easiest part.
>
> At 11:25 PM 8/25/98 +0100, 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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