It appears, despite the r/r recently of my valve cover gasket, Superblue is still having a bit of oil leakage somewheres. I can still once in awhile see smoke wafting from the area of the RF wheel arch while idling after the car has fully warmed up. I have now washed the engine bay are 3x, once with Gunk (a bit of a disaster, as posted earlier), then some Simple Green on the areas where oil build-up was clearly visible, and a 3rd time on those areas with brake cleaner spray. I thought the spotless cleaning would make it easy to see now where oil is coming from, but fresh oil is pretty much clear and if the leak is not that great is seems to be hard to spot on the engine.
Wondering if anyone is aware of any dye (or other substance) on the market that can be put into oil to make leaks more visible. The only other option would be to invest in some Royal Purple oil, although I hate the high $$ cost of that stuff (over 2x the amount of other name brand oils).
I’ve used the tracer dye for A/C systems to check PAS and Selespeed systems for leaks in the past. You need a UV lamp to see it - Home Despot sells a UV cured adhesive kit which comes with a small UV LED lamp for about 20$.
Are you sure its engine oil. Is crankcase level changing noticeably.2. Could it be ps fluid or tranny .3. Visual check… oil sender…front or rear seals…pan gasket…put red rosin paper on floor under engine area…look for spots…trace back as drip probably is starting elsewhere. …
Having dealt with tons of oil leaks on my old turbo Volvos, I would only use carb cleaner to clean off the oil. Brake cleaner can take off paint. And Simple Green is messy.
I would then let the car idle for a while, and look underneath for oil leaks. If none show up, perhaps it only leaks while driving. I would then go for a short 15 minute drive, and again look underneath for oil leaks.
If you’re seeing smoke, sounds like the leak is dripping onto the exhaust manifold.
Leaks from top of engine are super hard to find. I usually trace them up from below. And then look around for the obvious places. Valve cover. Oil cooler lines. etc. Since you just did the valve cover, there’s a chance it was not done perfectly?
Do you have a telescopic little mirror? Comes in handy for looking for leaks underneath at top of engine.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
8
If it’s dripping onto the exhaust manifold, it’s probably coming either from the cam cover or from the tappet block. Since you supposedly recently did the cam covers – and I’m sure you followed my advice rather than the Jaguar repair manual – that joint should be leak-free. Perhaps can be checked by literally touching the tappet block just below the cam cover and see if it feels oily.
That would leave the tappet block-to-head joint. The bad news is that’s a bear to seal, as it requires removing the cam and therefore fiddling with the timing chain tensioner. There’s a diagram in the Book indicating exactly where Loctite 518 should be applied during assembly. Jaguar used Hylomar, which is why it is leaking.
I have now washed the engine bay are 3x, once with Gunk (a bit of a disaster, as posted earlier), then some Simple Green on the areas where oil build-up was clearly visible, and a 3rd time on those areas with brake cleaner spray. I thought the spotless cleaning would make it easy to see now where oil is coming from, but fresh oil is pretty much clear and if the leak is not that great is seems to be hard to spot on the engine. 
