hello everyone. 18 years ago i've bought an xj6 1996 with 80k miles on it at that time. now is at 130k miles and there is a bit of long list of problems with the car. I will be trying, with your guidance, to diagnose and possibly fix few things. although I am lacking any mechanical background, and I own few basic tools there is a great enthusiasm
1) rough idle.
soon after latest oil change, I have added an extra half quart. bad idea most likely. soon thereafter the engine start to exhibit a rou

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soon after latest oil change, I have added an extra half quart. bad idea most likely. soon thereafter the engine start to exhibit a rough idle.
for the first time, even, after reading here, I decided to start the work. I have removed the valve cover and this is how it looks like (see attached).
there is oil in two spark plugs holes and one is dirty. will post as many details about so that the advice can be smooth.
the question I have now: is that how the head supposed to be? full of oil? how I can clean all the "junk" without removing any further parts?
thank you!

I thought that picture was unfamiliar. Although your car seems to be an SII, it is actually an XJ40.

Moat of us don't understand it. Only a very few masters in the heritage do.

Check the XJ40 forum and i'm sure you will get the advice you need

From my POV, the extra 1/2 quart had nothing to do with the rough idle.

Finding a lot of oil in any valve body is normal. Lots going on there that needs lubrication.

Check the plugs after removal. Sooty or oily not good. A nice light brown is ideal.

Good luck.

Carl .

The head looks totally normal. The bit of oil varnish and carbon isn't an issue and yes it should have oil all over. The oil pump pushes oil up into the head so it can lubricate the valvetrain. I'm assuming you ran it before you changed the oil and didn't run it for long after because the oil pooled on the head is pretty dark for just having been changed.

Anyways, none of this should really have anything to do with your rough idle. Even if oil was leaking from the cam cover and pooling up around the plugs, oil is non-conductive,so I can't see that causing an issue, unless you are saying the plugs were wet after you removed them. I would replace the gasket and cam cover and look over the ignition system. Maybe do a tune-up if you've had it this long and those things haven't been replaced.

+1 on posting in the XJ40 forum with your questions.

Clean the spark plug wells and then remove the spark plugs. With the spark plugs removed, spin the engine for two or three seconds to push out any lingering oil then put a small amount of anti-seize compound on the threads of new spark plugs and install them into the head.

Clean the cam cover gasket mating surface and install a new gasket on the cam cover then tighten to the correct torque using the sequence in the Workshop Manual.

thank you all! it is greatly appreciated taking your time and sharing your knowledge and well meant suggestions. I may have made the mistake to list the submission under the wrong forum. to clarify, the Jaguar is an 1996 XJ6. I was under the impression that x300 is what i shpuld be reading and inquiring about. I will be updating about the progress made

Sorry I didn't mention this, I figured you would just poke around after others mentioning the S3 forum is wrong, but yeah you aren't looking for XJ40 either. I'm not sure why others mentioned the XJ40. Xj40 is until something like 94, so yeah your 1996 would be in the X300 forum.

Everyone in any of the forums can give you general trips that apply to all cars, but the guys in the x300 forum know your car and maybe even know of a common issue to cut down on your diagnostic time, like a bad TPS or similar.