In reply to a message from ESLF16 sent Wed 12 Sep 2007:
It should be replaced if you want to extend the service life of
your supercharger. They are NOT sealed for life, though many
owners of imports using the M62 are being told they are sealed for
The oil begins as clear as cooking oil, almost totally
translucent. After 25,000 miles it will probably be grey and in an
other 25,000 miles darker still, not black but getting there.
You need a hand pump mechanism and tube to suck the fluid out of
the supercharger. The nose cone bearings and main bearings of the
supercharger itself share the same fluid. If you remove 6fl oz,
replace 6 fl oz. Much like transmission oil, you can only truly
flush the unit by replacing the expensive oil repeatedly or when
the unit is removed from the engine.
I believe the capacity of both the Eaton M90 and M112 which the
XJRs utilize from 1995-2003 is 8fl oz. It is an easy process to
suck the fluid out provided you find a tube small enough to insert
into the nut on the front, facing the supercharger nose cone, on
your left that is sealed with a single hex bolt.
Your intercooler shares the coolant as the radiator and when you
flush the coolant, flushing with distilled water and then adding
coolant is the best way to force most of this old fluid out.
On the XJR6’s, there is a nut on the top of the intercooler that
you could pour distilled fluid through with a transmission fluid
size funnel in order to push water through the intercooler, but I
have not tried this. The XJR8 might be the same way.
So to be safe, keep flushing with water until you get most of the
coolant out of the system and refill. Idle the car until it is
warm and then turn on the heater to its maximum temp/blower setting
and let it idle for an additional 5 minutes to circulate the new
fluids through the system and release any air bubbles through the
When I had my cooling system redone, I had it flushed with water
until nothing but clear water came out and it took two flushes and
10 gallons to do it. I was running 70-80% water if not mostly
water when I purchased the XJR. Even idling with the heater on, I
still had some air trapped in the system so its good to do this
heater on max process once after the coolant is totally cold and
brought up to normal temp the following day.
These two things, changing the supercharger oil every xx,xxx miles
and performing a coolant flush on a regular (some prefer 2 years,
some do it every year) interval will keep these components working
in the best possible shape.
I really am hesitant to go more than 30-40k miles before changing
the supercharger fluid. I’m going to measure it every 15k miles
and see how quickly it is being contaminated and it’s time to take
a sample to see for yourself how dirty it really is. Much like the
diff oil, it might go 100k miles with no fluid change, but wouldn’t
it be nice to go 200k miles by changing the fluid out 3 or 4 times
to reach the 200k mark?
Sunny Garofalo, '97 XJ6, '95 XJR
Northridge, CA, United States
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