According to my 1975-1980 Bentley MGB manual, both the non-overdrive and
overdrive transmissions get drained and refilled at the "A" service @ 1000
miles
(referred to as the "After Sales Service"). There is no other mention of
changing the non-overdrive transmission oil, just "check and top up" at the
regular
service intervals. However, the overdrive transmission is to be drained and
refilled at the "E" service intervals every 25,000 miles. The only service I
can find mentioned for the rear axle is "check and top up" if necessary, also
at every service interval.
On the other hand, my 1962-1978 Haynes MGB manual recommends draining and
refilling the gearbox every 12,000 miles. This is noted both on pg. 8 of the
routine maintenance section and on the first page of Chapter 6, the Gearbox
section. In the Rear Axle chapter, under section 2 of routine maintenance it
is
recommended the differential be drained when hot and refilled every 12,000
miles.
My guess is, that with the improved efficacy of today's lubricants, you could
probably stretch your oil changes out to 24,000 miles or say...every two
years. Now, considering you have never changed the oil in either unit, it may
not
be much of an advantage for you to do it now. Let's see what kind of
opinions the rest of the list has.
Hope that helps!
donny v
1978 MGB
(P.S. It should be noted the manufacturer service intervals are based on
driving the car approximately 12,500 miles per year. If the car is driven
substantially less miles yearly it is recommended the "C" service be carried
out
every 6 months and the "D" service every 12 months. - that's from the 75-80
Bentley manual)
In a message dated 4/4/2004 5:22:33 PM Eastern Daylight Time,
Pointparty@aol.com writes:
Is it necessary to change the lubricant in the differential or in the
transmission, ever? Mine has never leaked. Neither the tranny nor
differential has
never been removed. I drive the car a few thousand miles each year.
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