1994 Jaguar XJS Tuneup Questions.

[Serolim]

Welp, I'm back with another car concern, many thanks to those that helped with my previous post.

4.0 Engine 4l80-e trans, only 60k miles. Pretty much a cruising the coast car / sonic stop & dine / beach trip car.

Much before that it was a show car from another collector. Everything on the car is original.

Anyways, I like to start new when I get a new car, new oil, coolant, transmission fluid and such so I know what's in there. So I'd like a much more in tune person/s take a look at my selection of tune up choices and voice any concerns.

Spark plugs will be NGK iridiums. Factory is copper.

Oil will be Delo 10w30 HD synblend oil, SN rated. Has no oil leaks, unknown what's in there.

Coolant G-05 pretty much what I use in everything.

Transmission fluid - Valvoline dex 3 conventional. Only sump 1 gal through dip stick tube each year, to slowly move fluids as I don't like full flushes on the unknown, fluid is still bright red.

Differential fluid - idk... ik I need a gl5, and a 90sae or 80w90. It's positive traction, and from what I hear, ford's blue tube of addictive works great in it. I also know synthetic Isn't wanted in it via the manual. Why? Due to natural rubber/leather seals.
I don't think that'll matter but better safe than sorry, and it's got a fill and drain bolt, easy with a pump. So any advice on that oil would be most appreciated.

Bought it at cruising the coast so limited info on it from seller, mostly told me about the oddity Features of the car.

Thank you in advance.

 

[RooflessVW]

I'd advise against the iridium plugs. Use the OEM or at least OES plug.

 

[Serolim]

Originally Posted by rooflessVW
I'd advise against the iridium plugs. Use the OEM or at least OES plug.


Care to explain why? I've used double plats or iridiums in many old engines iridiums seems to work great in carbed engines. Tho, I've never had a spark plug issue either, minus Bosch plugs in a GM trailblazer 4.2.

 

[clinebarger]

Are you sure it has a 4L80E? While the V12 has this unit.....Never seen the I6 have a GM trans behind it.

 

[Serolim]

Originally Posted by clinebarger
Are you sure it has a 4L80E? While the V12 has this unit.....Never seen the I6 have a GM trans behind it.


Haven't crawled under it, but that's what it says it has according to papers and auto part stores when parts looked up.

 

[Lolvoguy]

Originally Posted by rooflessVW
I'd advise against the iridium plugs. Use the OEM or at least OES plug.

+1
Despite their claims, they can actually cause more problems (rough idle etc) on older cars that were not specd for them.

 

[vitez]

Oh my...........

Check out jaguarforums.com, look at the X300 section. It'll have everything you need to know and more, actually enough to be really worried.

I say this having owned a 97 XJ6 and and 96 XJR. There's nothing more expensive than a cheap Jag! No offense if yours is in excellent shape! My XJ6 was a beautiful car, well looked after, ran well with only a few small repairs needed. Then it was written off.

Still having the Jag bug I found a local XJR. When it ran well it was an awesome vehicle, but it rarely ran well, and then the rust started. I ended up donating it to a charity after 6 years and an embarrassing amount of money spent on repairs.

Just use Champion Copper plugs, the X300 engines were spec'd for them and they can run better with them than newer designs.

HDEO is a good choice, but in your climate I'm quite sure Jag spec'd a 40 wt. I used Amsoil AMO 10W-40 in both and I'm in the Canuck prairies.

G-05 is perfect.

I too believe the GM trans was only installed with the V-12 or the supercharged 4.0. My XJ6 had the ZF trans, my XJR had the GM.

Differential fluid: Amsoil 75W-90 Severe Gear. I use it in pretty much everything, and you rarely need to add additional limited slip fluid.

Coils: big issue! The X300 engines were the first Jaguar coil-on-plug engine AFAIR. The average coils now available are made in China garbage. They can fry even in a few months. The factory Lucas ones were made in Japan. The Japanese supplier still makes them just not labeled Lucas. You have to make sure when you order if it is indeed the made in Japan one.

I'm glad to get rid of my XJR headache, but when it was running right I had it up to 240 kph and it purred like a contented cat. Even the XJ6 ran beautifully at 220 kph. Sounds like you have fabulous cruising vehicle. Maintain it right and enjoy!

 

[clinebarger]

Originally Posted by Serolim
Originally Posted by clinebarger
Are you sure it has a 4L80E? While the V12 has this unit.....Never seen the I6 have a GM trans behind it.


Haven't crawled under it, but that's what it says it has according to papers and auto part stores when parts looked up.


It has a ZF-4HP24, Earlier I6 4.2L Jaguars had Borg Warner autos. Earlier 5.3L V12's had GM TH400's behind them.