":::Jerry::::" wrote in message
...

You are missing the point, the same can be true even if the recommended
oils
and change periods are used, it is also true that engines and
transmissions
can fail even if the best oils are used, life of components has far more
to
do with how the car is driven than what oil might or might not have been
used - keep trying to 'crash' through the gears and any transmission will
have it's life expectancy shortened.

The point is not vehicle abuse.

Rather than spend extra money on expensive 'snake oils' you are just as
likely to improve the life expectancy of engine components by using the
recommended oils and just change them more frequently.

Some people seem to think that makers only recommend cheap mineral oils
unless otherwise stated. That is not the case. Makers recommend a viscosity
and API rating. Some poor oils may meet that and most high quality full
synthetics meet and exceed the API by a long way. The difference in quality
and protection of the oils at each end of the price scale is marked.

Full synthetic oil is not snake oil. Its benefits over run of the mill
mineral oils is beyond question, and I have no intention of going down the
synthetic vs mineral argument. My automotive engineering friends, not
mechanics, say that Slick 50 in the gear box will prevent wear. I believe
them. :-) Slick 50 g/box treatment is not a one off treatment like the
engine version. It has to be in at all times.

I don't agree that a gearbox that has been treated with respect needs it's
oil changed to a (so called) higher spec',

You put the spec in the makers say. It is the quality of the oil that
counts. Full synthetics are miles ahead of mineral oils. I don't believe
that a gearbox is sealed for life, unless it has an oil filtration system
and full synthetic from new. Gear oil "does" deteriorate with use, that is
certain. Some makers specify changes at 27K miles, about every 3rd service
or roughly 3 years. Changing at every 2nd service and using the best
synthetics is very, very wise to keep that smooth newness for the majority
of the cars life. It does work, I assure you.