Got my 1988 XJS six months ago and after installing new fuel pump, filter..i got it running. Now i am ready to change the oil filter and transmission filter . Any suggestion(s) what kind of oil would i put. any website to show me on how to make changing the fluid not complicated ? What would be the best oil for it. Thank you all for the advice..it really helps me alot and yes..i love driving this thing....

 

I have a 93 XJS 4.0. If you have the same engine, I believe both fluid changes are fairly simple. I use 10/40 oil, being that for about the first 20 years of this cars life, they didn't have syn. oil, I would not bother using it. Just make sure you use a name brand oil and filter and try to change it every 3 to 4 thousand and if you do not reach that over the summer, then change it every spring and fall. The oil plug is on the drivers side of the pan, so make sure you jack it up high enough and use floor jacks for safety before you get underneath the car. I believe the plug is a 17mm. The filter is also on the drivers side and can be removed from up top side of engine compartment.
As for the trans., I did mine several years ago and really don't remember any issues, but I also don't remember how I did it.

 

there isn't anything complicated about the oil really. Warm it up a bit so the oil isn't too runny, but give it a good 10-15 minute cool down for all the oil to settle back into the pan.

Drain the oil out and then remove the filter (careful of the catalytic converter)
replace the drain plug and replace the new filter, with a coating of oil on the gasket and the filter filled with new engine oil to help prevent dry start wear.
use Jaguar spec oil depending on your climate, in florida mine seems to like 10w40 and 20w50 mostly. Unless the engine is brand new or has absolutely zero leaks and fairly new seals, I would not put Synthetic in it. Use a good known brand of oil and like mobil 1 or castrol and fill , checking the dipstick during the last 1-2 quarts.

I believe the tranny mount has to be loosened some to get the pan off the tranny in order to do a fluid change. Maybe wanna do a bit of research on this, basically it is sprung and needs to be supported by a jack like any large spring until the tension is released. Just work like you normally would and don't be scared off by the many people who are deathly afraid of the tranny mount.
Its a GM tranny, so the filter change isn't complicated, id try to find the correct torque spec for the filter somewhere, as well as the pan bolts.

remember the tranny capacity is in PINTS and not in quarts

 

@Side. Spot on with the transmission. You need decent clearance to work under the car (post lift is a godsend) and you will need to loosen off the exhaust that runs over the bottom of the tranny (at least I did). I notice then you just mention the tranny filter and gasket - check the mount while you are down their its almost certainly jelly. Take the weight of the transmission on either a transmission jack or normal jack / wood combo, lower it off the spring after undoing the bolts (9-10 off the top of my head). Kirby's book is full of good advice on this - slacken off the rear pan bolts more than the front so the pan tilts slightly and you can catch the fluid or you are going to get very sticky and red...... Once the pan is off, make note of the mount arrangements, dismantle replace as necessary then reassemble in reverse!




Fluid is Dexron 3, the stick says 2 but don't panic its backward compatible. Personally I think this is the worse smelling car fluid on the planet so steady-on!

 

Because there is no drain on the transmission pan, your first filter change will be a messy one. Just accept that fact, and prepare for it by covering your garage floor or driveway with cardboard, newspaper, plastic sheeting, or anything that will help with a speedy cleanup.

Two things that I recommend you do while you have the transmission pan off. The first is to install a Shift kit. The transmission is your standard GM Turbo 400, so there are plenty of kits available. I installed, and highly recommend the kit offered by TransGo. It firms up your shifts, and allows you to hold 1st and 2nd gears to any RPM up to redline, The stock trans will upshift at a given RPM, whether you want it to or not. Here is a link to the kit I'm talking about at Summit Racing: http://www.summitracing.com/parts/trg-400-1-2/overview/

The second recommendation is to buy a cast aluminum trans pan with a drain, so your future fluid changes will be tidier than the one you are about to undertake. I bought this one, also from Summit Racing. It's a nice, thick casting, so it won't deform and cause leaks, like the stock steel pan will, if you overtighen it. It also has a magnetic drain plug to catch any metal shavings that might be circulating in your transmission, and it's polished so it looks purdy: http://www.summitracing.com/parts/sum-433884/overview/