Several years ago I had the front oil seal replaced in addition to other items being repaired/replaced. Several days later, I noticed the new seal was still dripping somewhat, but nowhere near as bad as the one that had been replaced. A Jag enthusiast I’ve known for some time suggested when doing an oil change, to not fill past the lower end of the ‘knurled’ patch on the oil dipstick. This method did help considerably, but after a drive I’d always notice a few drops on the oil pan after while. Ten days ago, we took a 100 mile drive which included various driving conditions from 80 mph freeway speeds to several slow crawls due to traffic congestion. After returning home, the dipstick level appeared to have dropped an inch (2.5 cm) below the bottom of the knurled patch. I added a quart (close to a litre) to bring the oil level back to the lower portion of the dipstick. Yesterday, I drove the car 25 miles (32km) at highway speeds . When I returned home, I crawled under the car (as usual) to check for the usual drops of oil on bottom of the oil pan. There were none. I checked the oil level on the dipstick, which was still close to the bottom of the knurled patch, as it was when I began my journey. Could the 100 mile drive ten days earlier possibly have cured the slow leak?
Mel R.
This is going to get esoteric but I think it is possible that the heat and long drive cured it. Parts get soft and have time to move. Dirt may be washed out. Long distance driving seems to cure so many things.
I also keep mine low, but then I have no dipstick to check with. The tube broke off flush some time before my ownership. Anything higher than low seems to disappear quickly.
Thank you, David. I sure do hope your theory is correct. Time will tell. Thanks again.
I agree with David: running low on the hatching would help with oil burning (not so much tossed up into the crank/pistons), but would have little effect on the oil being flung around by the chain stack.
As you say… time will tell: keep us posted.
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I don’r really think that dropping oil level is an appropriate solution to an oil leak, Mel…
Admittedly; if you fill to the ‘full’ mark on the xk; the engine will very quickly burn off a pint or so, wasted - but, apart from lubrication, oil is a necessary cooling agent for the engine. And on long trips at speed; starting with a low level is a bit iffy - and the dipstick is there for a purpose…
A properly installed front seal should not leak, and that it should seal up with time is somewhat dubious - but good sealing requires smooth mating surfaces and a proper fit.
‘Fill it up and see what happens’ is a bout as good as it gets - and it would help to know exactly how much oil is lost under various circumstances?
Frank
xj6 85 Sov Europe (UK/NZ)
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But it is! We’re not talking oil pump starvation here. Even though the engine can briefly live with that. There will not be a noticeable cooling difference with a quart more or less. The question is whether overfilling to satisfy the dipstick reading is better than keeping it low and keeping an eye on it. Either one burns a lot of oil unnecessarily or one has to refill more often - clearly it is not losing much oil now, whereas before it went out the front seal. Which might have seated better now, or there was a hair trapped inside, or a little leak has clogged up or who knows what.
As I said I have cured many issues by long distance, high speed driving. Some problems come and some go.
David
Thank you both Frank & David. Frank, I’m sure you’d understand I would prefer to go with David’s line of reasoning on this for obvious reasons…
I’ll just continue to monitor the situation and report back with updates. Time will tell…
Mel R.
Mel,
as Frank confirmed it is common experience that a sump filled high on the knurled marks or even above with oil will dispose of the “surplus” quantity quickly and the reason for that has been described correctly as well as more oil fumes will get drawn up into the combustion chamber and burnt off.
Whenever noticeable quantities of oil are lost, it is practically always an indicator of an engine problem, as large quantities can only be burnt off. If you have to fill up a quart after 1000 mls and this quantity were just leaking away your car and its environment would look like the Alaska coastline after the Exxon Valdez incident.
Oil burning may be caused by blow-by passages caused by carbon deposits which again may be cleaned off by serious driving.
(Small) Oil or p/s leaks will always certainly be reduced by regular, frequent and extended use, as engine and gearbox oil won’t have as much time to pour down and put stress on the lowest seals, as rubber seals will swell and as small quantities having leaked out nonetheless will be “worn off” more likely.
So, by all means - drive the car and keep an eye on the dipstick!
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec)
You all are seeing this phenomenon? It’s SOP for the XK engine?
Yep, tried to keep “central” in the knurled area as per the book for the first months, but kept filling up half quarts. After some time I decided to just see how long it took to use 1 quart, so I stopped refilling and found that the level stabilized around the lower marking of the dipstick. Now I only change oil every other year independent of mileage (usually around 1000 - 2000) and do not fill up at all.
Best
Jochen
75 XJ6L 4.2 auto (UK spec)
…and always carry a spare liter or two, in the boot!
Now THAT is perfectly normal!
The rest is correct, and if the level were dangerously low there are signs (dropping oil pressure on deceleration and a flickering oil light ultimately). I always carry oil (not in the Mercedes which warns me early) and water and always have.
Jochen, Wiggles, and Kirbert, thanks for your advice. I am feeling more hopeful now the problem is now hopefully solved. A fellow local club member told me he encountered a similar slow leak condition on his series 3 car oil seal which he cured by no longer filling the oil level in the crankcase higher than the bottom of the knurled patch of the dipstick. And yes, Wiggles, I always carry a spare two quarts in the boot, and check the oil level on the dipstick before and after each journey. Updates to follow…
Mel R.
Mel R.
I know it is perfectly normal (even though all of my cars consume less). And yet, my point was, if you lost one quart over 1000 mls through leaks alone your engine and everything around would be a mess!
Best
Jochen
75 XJ6L 4.2 auto (UK spec)
My ‘66 ‘S’ used to use oil when I drove from Auckland to Wellington, minimal to nothing on the way home, I think it came down to slight glazing of the bores due to around town slow speed travel against the more spirited drive down to Wellington.
Thanks for that info, Robin. In my case, however, I think it all comes down to that replaced front oil seal, and i’m hoping it has finally seated properly. I’ll keep monitoring the situation.
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While monitoring the situation, Mel; check the filter etc of the crankcase ventilation system…
Improperly working ventilation will increase sump pressure - increasing leaking and oil consumption. This is of course only valid while the engine is running, it has no bearing on a ‘standing’ leak…
Frank
xj6 85 Sov Europe (UK/NZ)
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Definitely check crankcase ventilation and that mesh filter. Mine leaked badly originally but a PO had decided to completely block the crankcase ventilation with a piece of flat rubber sheeting cut nicely to size. Removing that solved the oil leaks and it really wasn’t blowing much through anyway. Even partly clogged, the mesh filter builds up some back pressure to force oil out.
OK… NOW I’ve heard it all.
You may remember, Frank, several years ago this car failed emissions test, idle was a bit higher than it should be. Several ‘less than scrupulous’ mechanics said I probably needed a catalytic converter. At that time, you suggested the cause of the improper idle might be a vacuum leak somewhere. After checking every air hose, I noticed I was missing the mesh screen item which fits in the bulbous section of the hose on top of the crankcase, and even without the mesh, that hose felt loose. I ordered a proper mesh filter from SNG, installed it, and , when placing the hose back on top of the crankcase, placed a clamp on that hose to ensure a snug fit. This remedy decreased the warm idle speed to 800, where it should be, and the car passed emissions test with ease later that same day. Thinking back , I remember having had the front oil seal replaced several years ago after it began to leak noticeably. From that time forward, I noticed, after a run, there would still be evidence of a bit of oil ‘seepage’ from the new front oil seal, but nowhere near what was coming out of the old seal. As I mentioned earlier, a local club member suggested not to ever fill the crankcase oil beyond the lowest mark of the knurled patch , which helped a great deal. What started my original posting on this topic several days ago was my delight at the unexpected reduction in seepage. So, all in all, I will continue to monitor the level and report back to the list. Thanks again
Mel R.