I will be changing the oil this weekend for the first time in my new to me XJ8.

I noticed some white deposits on a few of the spark plugs which can indicate leaking valve seals. My research has found that a good "high mileage" oil can help condition these seals and reduce the amount of oil that is getting by the seals and being burned.

I have no other indication of burning oil like a blue cloud or anything but I figure while I'm doing the oil it can't hurt.

I'm thinking of Mobil 1 High Mileage unless someone has a better idea.

I figure I will do 5K mile changes.

Also, if I can't get my hands on a genuine Jaguar filter what's the best alternative? Purolator and Bosch?

Thanks in advance.

Eric

 

If your plugs looks like the top one in this link:

NGK Spark Plugs USA

and you're not using an appreciable amount of oil, I'd keep using the same brand and not fool around.

Using synthetic oil with a 5K change interval is a waste of money, but do what makes you happy.

 

This is the forward most plug from the right bank. The deposits are thick enough to have chipped off. Two others are maybe half as bad.
The rest are perfect. I don't think they had 10k miles on them.

Thanks

Eric

 

NOT Bosch.

You will receive a filter that is much shorter than OEM.

If they couldn't bother with making it the correct size, what else did they not bother with?

 

Mann filters are good quality and have a check valve. There was a lengthy thread on one of the Z3 forums a couple of years ago where some of the members found that the elements in many name brand filters were disintegrating, but Mann was good.

 

Engines that burn oil usually leave black oily deposits on the plugs-not white deposits as in your pic. If there's no blue exhaust smoke & the engine is not using more oil than normal, then just keep things as they are.

If you're going to change your oil every 5k miles, then don't bother using expensive synthetics-use a 10W/40 part synthetic which is lower in price & can justify being changed at 5k mile intervals.

 

Even 10K change intervals on conventional oil would be good enough. The engine has a big sump so there is far more capacity to suspend contaminants. 5K filter changes might make you more comfortable with this.

As Red October said, your plugs don't show any sign of oil burning.