Hi all, I found a 99 XK8 Cabriolet that was needing a new home and I just happened to have a vacant stall and some time on my hands. I started out with little things that are easy enough to do just takes a little time and patience. I was impressed that the she had a little over 105,000 miles and no oil leaks.
Naturally a wanted to get acquainted with my new girl and wanted only the best for her so I purchased Royal Purple Syntetic 5w 30. I haven't really driven it more than 10 miles since the change but oil is dripping off the pan. I got her up in the air and cleaned her up real good. I was hoping I may not have gotten the new Royal Purple filter tight enough. I have never had that happen before and this time was no different.
I can't help from wondering if This isn't a reaction to the good stuff. Perhaps I should have stuck with Dino oil of the 10w 40 persuasion.
Anyone ever switch back for a leaky reason like this? Did it help? Thanks for any suggestions. Luff

USA
1999 XK8 Cabriolet BASE

 

Basically, dino oil has molecules of different sizes and the larger ones plug up passages. Synthetic has molecules of the same size, and smaller, so it will leak through small passages that the larger molecules will not. You should probably go back to a dino oil.

Now, let the traditional oil wars commence. You will have a thousand different views on this, just pick the one that makes you happy.

 

I opened the thread so may as well comment. Sad your oil leak has appeared but hard to think that the oil was the problem,maybe a coincidence.

But not prepared for the ensuing oil debate that usually follows,although I agree with your choice.

Maybe it was just time for a pan gasket no matter what the oil was. Good Luck with it.

 

This is a known issue with no need for starting any "oil wars". As Kevin D accurately pointed out, synthetic oil can get through barriers that conventional oil often cannot. Some say synthetic oil creates these leaks. It does not. It simply exposes and slides through them. Most folks who encounter this issue switch back to conventional oil and the problem disappears. That's what I would do, and this (along with excessive cost) is the primary reason why I have never used synthetic oil and have no plans to do so....

 

Wait a minute- you JUST bought the car, changed the oil and any oil leaks must therefore be caused by the oil type?

Even if the stories and theories are true, it's not going to be noticeable in 10 miles.

How about changing back to regular oil to see if the leaks stop.

BTW- Royal Purple is no better than any other brand, it just carries a premium price tag to pay for all the marketing hype they flood the market with..

 

I don't want to open a can of worms but was hoping for validation of my theory. I don't think the leak is coming from the pan rather oil working its way down to the lowest point. My thought is the rear main seal.
I called the previous owner and he insisted he always requested mobil 1 be used but didn't know what grade. He had no recall of the partialy used quart of Dino in the trunk.
I know 5w 30 is appoiprieate for this time of year. 10w 40 May be more practical for this cat. I can always use the oil in my 06 Tacoma which has had Syntetic 5w 30 since the first oil change.
I will be getting under her Bonnet today and cleaning every thing. Useing in light and mirrors to try to determine the oils path. My wife thinks I'm nuts but I can't think of a better way to get to know this cat.
Thanks for your input. LUFF

 

Huh, previous owner used Mobile 1, leak is by oil filter, perhaps the old filter gasket was stuck to the block or the filter itself is leaking. Change the filter, check the gasket surface.

 

+1

I changed oil and filter once and got a low oil pressure idiot light after a few miles afterward. I checked and didn't find any oil on my dipstick. Seems the old oil filter gasket stuck to the block and I screwed the new filter right down on it. Double gaskets do not provide a better seal! Did wonders for chassis rust prevention though.

 

Drain the oil clean up the mess and replace it with 10w30 Mobile1 and see what takes place. I find it hard to believe that the oil you installed this leak that fast.

Gus
www.jagrepair.com

 

Determining the true source of the leak is critical here. It may have been pre-existing regardless of oil used and cleaned or flushed away by the prior owner or mechanic. Dumping a synthetic oil for dino oil may cure minor seeps but I have never seen it stop any leak that is significant.


BTW - I have been using Royal Purple 5W - 30 for the past 3 years on my 03 XKR with no noticeable leaks or seeps and I am particular about leaks and seeps. All my engine oil bearing gaskets are original.

 

No leaks around filter. Cleaned above oil pan all around. (Surprisingly easy to get all the way around) took her out for a nice run on some local twisties. Got her breathing really well. (Turning off the ASC really makes for exilerating drive.)
Put her back in her stall up in the air. Not a drip anywhere. Checked dip stick slightly above full. It looks like I had put in 6 and 3/4 quarts. Just a little too much? I thought it was supposed to use 7.4 quarts with filter?
I will wait a few days to see if any oil migrates down.

( FULL IS GOOD. BETTER THAN FULL IS A MESS)

 

That may be it! I have made the mistake on other vehicles and lost oil in new places including the rear bearing seal. Usually self cures once level is corrected.

 

The oil is still leaking from above the oil pan. I decided to replace the synthetic oil with Dino oil to see if it helps. Since the car is not going to driven until spring I put in 10 w 40. in her. If I only change the oil once a year, this grade would better protect her when warmer weather arrives and I begin driving her again.
I imagin that the weight of the oil had a lot to do with the leaking.
My 99 4.0 liter takes 6 quarts to get between the lower and upper dip stick marks. Don't over fill these engines.
I'll let you all know if this makes a difference.

 

I agree with Gus. I put 5W-30 in my 98 and had small seepage at valve cover gasket in the back. I drained and put 10W-30 and I didn't have anymore problems. I had recently replaced the valve cover gaskets and it had no seepage until I went to 5W-30. MHO

Tauni

 

I've read all the Dino versus Synthetic arguments many times but was interested to find the word bonnet used in West Virginia. I thought hood was universal across the USA.

Graham

 

Just trying to fit in��
Gwendolyn isn't my first British car.
Some of us in WV even understand why you blokes drink warm beer in the UK.

 

 

Jagwars have hoods, Jag-u-ars have bonnets