Hi forum. I bought a 1997 XK8 convertible just over a year ago, my first Jaguar and the car of my dreams when I had a young family and couldn’t afford one. 97000 miles on the clock and in good condition with regular service history. The previous owner had not run it much in the last few years due to poor health. A short period of what I would have called tappet tick on a push rod engine when I first got it that disappeared when warmed up and has not been a problem since. No start up slap. Engine running sweet. I have finally got round to getting the cam covers off and unfortunately it has second generation secondary chain tensioners and original primary. I am screwing my courage to renew the timing gear but I have also noticed quite a bit of oil crud in the recesses of the cylinder head, the baffles on the cover and on the surface of the VVT. The non contact surfaces of some of the cam lobes are stained brown but not worn/marked. My inclination is to do an oil flush but I have seen arguments online against because of the risk of leaking oil seals. Thoughts/advice welcome

 

If it was my car I would run a quality synthetic oil such as Mobil 1 for a couple of short duration cycles. Like 250-400 miles each. Personally I use 0w-40, which is right for my climate, but use the viscosity recommended in the owners manual for your own temperature range.

And I’d definitely run that 250-400 miles all in one day, then change the oil and oil filter when hot . Stretching out the mileage over a longer period of time will not get you the same cleansing result.

After 2 of these abbreviated oil change cycles then check again under the valve covers. You should see a dramatic improvement.


Z

 

Not familiar with what you mean by "oil flush", I have never heard of that procedure before.

You could drain 1qt, top off with ATF then run that for a few hundred miles before changing the oil completely. ATF has dispersants to break down those sort of deposits and there are others on this forum who have done that.

But if you have no unusual noises or other concerns, my inclination would be to just run a good quality synthetic oil along with a good filter and change it more frequently than normal the first few times.

 

It used to quite common years ago when oil quality wasn't so good.





The aim is to clean accumulated engine sludge and deposits.

Graham

 

If it is not super dirty, you can try a product like Seafoam. It is supposed to be added 100 miles before an oil change so it has a chance to clean thing up and is then quickly flushed. Definitely follow the directions on the bottle, I believe it recommends keeping an eye on the oil to make sure it is flushed early if it becomes too dirty. Maybe throw in a replacement filter halfway through.

To my knowledge, some on this forum have had to deal with cars that had "never" seen an oil change their entire life. A lot of crud/sludge to handle after that, but ended up working just fine in the end. It would not hurt to clean all accessible surfaces by hand in advance of any treatment, now that the valve covers are off.

You already understand this, but the risk of an aggressive cleaning on a super dirty engine is to dislodge too much crud at once and somehow plug something up.

 

I haven't used a flushing oil in more than thirty years.

On any "new to me" vehicle, I like to do an immediate oil and filter change and then repeat within 500 miles. Three reasons:

1. it removes any doubt about the timing of the last or previous oil change regime
2. it gives me a baseline for future oil change intervals
3. I know for certain exactly what oil is in the engine

Difficult to describe what looks "normal" but this is my 2001 XK8 at 80K miles. Always serviced on schedule and using synthetic oil:








It's a clean engine and cam cover - typical of most I see.

The arguements against flushing are usually the same ones used against changing from dyno to synthetic oil - it leads to leaking seals. Can't say I've found that to be the case.

Graham

 

The previous owner of my car had regular services at Tom Lenthall Ltd (a main Jaguar Dealer). Old receipts show that either 500ml or 1 Ltr of Engine Flush was used every service oil change but only after the car had reached 70,000 miles. There’s no mention of it in the service plan and I imagine it was a policy change? It seems like overkill as the car was only doing about 6000 miles per year (Now over 100,000 miles). But there may be reasons behind it so now, because I do my own servicing, I continue with the annual Flush. I consider that my engine is used to it and it only costs £10. It's definitely cleaner inside than out....!

 

Thanks for the advice and opinions guys. I am getting back to my own mechanics after a break of more than 20yrs and things have moved on.

I think I will go with the rapid oil change cycle recommendation as well as a manual clean of all the surfaces I can reach. As I will be raising the car up I will also drop the sump and give that a clean while I am there.

 

avoid flushing unless the engine is a disaster. Example: i have a car, 2001 Honda that ran on quality dino oil for its 65K miles. Changed twice a year due to type of service as recommended in the manual. My mechanic friend who would adjust the valves for me would tease that it was "dirty" inside with some of that heavy varnish staining which is normal. He would say that i was not changing the oil enough. We were, still are, good friends, so there was nothing rude or dishonest. A few years ago before i put this car in storage, i permanently switched all of my vehicles to full synthetic oil of very high quality. Two, (2), oil changes with the same service, however now i let it go for a whole year. After just two oil changes and two years, he is adjusting the valves and telling his friends hanging around at his shop, "Wow, this engine is clean." These guys were telling me that they could not believe how good it looked inside. I guess that the varnish was gone, and he forgot about how he liked to bust chops of which i reminded him.

Moral of this story is to start simply doing the right things before using an intervention chemical.

BTW: i have a vehicle that gets maybe 1500 miles per year. Just for fun installed a very good synthetic rated filter and high end synthetic oil. Left it in three years. Only thing that i did differently was that if it was going to sit for a few weeks or more, the car was turned off after the oil got really hot. Tested the oil, was good for probably another three. Opened the valve cover and it was extremely clean even with neighborhood driving.

 

if you have light varnish use redline (not the professional series) or something else with a decent amount of ester.


by second do you mean the metal ones or plastic with springs? don’t worry about the primary stuff