XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

A couple of simple transmission questions

Old 04-20-2019, 12:23 PM
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Default A couple of simple transmission questions

One, my XJ-S has ~63K miles on the clock, and I can't remember if or when the transmission fluid was changed. There is great little local oil change place (not a chain) that I take my Range Rover and daughter's LR2 to, and the last time I was there they were running a special on a trans fluid and filter change so I asked the owner about the Turbo 400 in the XJ-S. He said bring it by and he'd check if it needed it, and he said it didn't -- fluid was cherry red, smelled exactly like new fluid, etc. However this morning I had a car show on in the background, and they made a comment about how you should change the fluid no later than 60K miles, and that if you didn't damage would begin. Should I change the fluid anyway?

Two, is there any reason not put in B & M modulator? Seems like the easiest and cheapest performance enhancement possible on the XJ-S. Does anyone have experience doing this?

Old 04-20-2019, 01:18 PM
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B & M adjustable modulator a great idea, you can adjust the change points to your liking.
If the fluid is bright clear red you do not need to change it. The fluid change is easy enough to do, but the Jaguar installation of the GM 400 has an anti-shunt device on the rear that must be undone before the pan can be lowered.
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Mac Allan (04-21-2019)
Old 04-21-2019, 06:41 PM
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Mac Allan,

I agree with Greg re. the colour.

A basic fluid and filter change is fairly easy. However, for me the bigger issue is that if you just drop the sump, you'll only get out less than 1/3 of the total fluid. So, having completely flushed my 4.0 24 months ago, I've then introduced a different regime of just extracting the fluid from the sump using a vacuum extractor pipe down the dipstick every year and replacing that much fluid. That way. I'll keep fairly clean fluid in the system all the time. I'll then do a full flush and filter change again after another 48k miles from the last full flush.

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Mac Allan (04-21-2019)
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