Charles:
I agree that an owner's manual is not a history book, my point is that
it is a historical document and may or may not be relevant 25 years
later.
As an example, when researching tire sizing I was amazed to find that
the industry specifications had changed dramatically during that time
and current aspect ratios are very different than those assumed in the
factory books. This specification drift is also true of currently
available oils. These differences were true even at the time of
printing, research in the 80s determined that the additive packages in
US specification oils were very different than those in the oils
originally specified by the British manufacturers.
I'm glad that my last paragraph was found to be humorous, as I also get
amazed at the gospel spoken by many gurus. I don't take myself to be a
guru and hope that my indication of lack of current research was taken
as proof thereof. Please note that my last paragraph indicated a lack
of specific recommendation, such as brand or additive. My conclusion
was an agreement with your statement that I have never seen any harm
with using regular engine oil. Personally I'm of the opinion that
regular oil changes with anything wet and squishy is going to give
better service than the eratic maintenance that many cars including my
own receive.
To that end, we have been researching and collating some reasonable
recommended service intervals based on original factory documentation
(historical) :) and long term ownership experience. Not guru advice,
but hopefully a reasonable guide to ownership based on modern real world
vehicle usage. I would be interested in any contributions or directions
towards suitable material.
Briefly, the Rover/Triumph 5 speed gearbox uses a fiber gear oil pump to
feed pressurized oil to the main bearings. The original UK
specification was 90W oil which was too thick for the cold winters in
the US. The thick oil would cause the fiber gears to fail causing
bearing failure. The factory came out with an update recommending
draining the gearbox and refilling with automatic transmission oil.
This of course created a continuing debate about which type of auto
trans oil to use. As noted above, so long as it is wet and squishy the
gearbox seems to be quite happy. Since the oil is being used as a
lubricant only and not for it's hydraulic drive properties the
difference between types is unimportant.
Kelvin.
Subject: Re: Oil for Overdrive Transmission
Kelvin,
An owner's manual is not a history book. It's a recommendation by
the manufacturer's engineers, based on tests that they ran before they
published the manual. These tests were run using the lubricants of the
time. Lubricants and their additives have improved over the years.
Where history comes in is the publishing of opinions by various "gurus"
as the years pass. So much of this is published that it takes on the
appearance of fact. Here's an example: John Twist maintains that
overdrives don't cut wear and increase gas mileage. He won't budge off
of this opinion despite evidence to the contrary. Hence, there are
Twist followers who believe ODs are not desirable.
I know of no evidence that multi-viscosity detergent oil has harmed
an overdrive transmission. Until I see some, I'm going to stay with the
factory recommendation.
I do get a kick out of your last paragraph. One the one hand you say
you don't have a clue as to what to recommned. Then you go ahead and
make a recommendation. ;^)
Cheers,
CR
P. S,: How about some more info on the Triumph/Rover gearbox problem?
|