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Guys, I just wanted to post this for future reference. I saw speculation, but I don't recall seeing confirmation of this solution in our archives.
I began to get low oil pressure exclusively on cold days. It would often show pressure a second or two before my RealGuage low pressure alarm would go off. As time went on, it began to take time to show on warmer days. In any event I got oil pressure registered within a few seconds.
This all went away after changing the oil and filter. All works perfectly now. Hope its that easy for you too.
Since a new oil filter (and oil) change fixed it, sounds a lot like a failure of the anti drain-back valve in the oil filter. Allowing oil to drain away from bearings..... There could be other causes, but that one is least complex.
Several alternative filters look the same and will fit but the anti-drain in the OE specification filter is critical to prevent the filter emptying when the vehicle is parked with slow pressure build up as the filter refills on startup.
The anti-drain is simply a silicone flap behind the perforated baseplate at the top of the filter. Oil pressure keeps the flap away from the baseplate allowing unrestricted flow when the engine is running. When the engine is stopped and no oil is being pumped around, the flap is held against the baseplate by the weight of the oil in the filter which prevents it draining.
Not exactly "high tech". Any distortions or splits in the flap render it ineffective.
even with the oil filter being horizontal, I can pre-fill it up with oil (about halfway) before installation without spilling any when starting the threads.
Not perfect, but that does reduce the "low oil pressure time" significantly.
Basically, root cause is typically bad oil.. Always use good oil filters, not the cheapest you can find. These are not expensive parts, and easy to fit as part of a regular service regime and should be changed more regularly as the car gets older..... BTW XK8s' ages are getting on .....
One of the people at, Blackstone Labs told me recently that our engines should be expected to last in the 400,000 + mile range before an engine overhaul is needed due to wear, as long as one is using a modern quality oil, / filter and they get changed at the proper milage intervals and time-wise, at least once a year.
am I wrong in thinking most X-100 owners here have cars with under.200,000 miles on them ? Whatever our average odometer reading may be, I pretty sure, that at least in my case, I'll be wearing out before the car does, despite my efforts to spin the odometer as often and as long as possible.
PS, re Blackstone Labs, I admit I'm hooked on their service. The oil analysis is a fascinating snapshot into the engine's health. https://www.blackstone-labs.com/
Interesting, but sending samples to Blackstone Labs is a bit beyond most people's pockets. I did note that Ed China, ex-Wheeler Dealers mechanic on TV, did do a TerraClean on the XK8 engine he had. That's more up my street.
Another question - if sulphur wasn't a problem, do you think the now-defunct Nikasil engines would last longer than their replacement engines?
Interesting, but sending samples to Blackstone Labs is a bit beyond most people's pockets........."
$28 for an oil analysis and $10 more for the TBN base additive numbers. Combined that's less than a tank of gasoline. done at every, or every other oil change, it hardly hurts the wallet at all.
@Zray -- just curious what viscosity range oil are you using. i am having good results with 0w-40.
regarding the costs of items and services there is an unwritten rule on the internet forums that one is in violation of some sacred covenant unless and until he spends an inordinate amount of time and frustrations [sic] to spend as little monies as possible regardless of the proportionality of the cost relative to the activity at hand, here a higher end automobile. even those of us who are very frugal in all of life get chided for daring to not do something as cheaply as possible even if it means future damage or inconvenience or worse injury. gods forbid we volunteer that we hired a professional to do something or did not live with some basket case situations while spending close to a decade weeding through problems in the most inefficient ways possible. this is not directed at everyone of course, and we all respect a person who does a workmanlike job with great savings and efficiency. it is a form of narcissism boring at best.
@Zray -- just curious what viscosity range oil are you using. i am having good results with 0w-40.........".
I use Mobil 1 0w-40 and the stock Jaguar oil filter. I'd probably use a Mobil 1 oil filter if I could find one. As far as I can tell, the one they were making for our cars cars has been discontinued.
so far so good. I'm only 13 months and 18,000 miles into my ownership. No oil consumption between oil changes.
...
regarding the costs of items and services there is an unwritten rule on the internet forums that one is in violation of some sacred covenant unless and until he spends an inordinate amount of time and frustrations [sic] to spend as little monies as possible regardless of the proportionality of the cost relative to the activity at hand, here a higher end automobile. even those of us who are very frugal in all of life get chided for daring to not do something as cheaply as possible even if it means future damage or inconvenience or worse injury. gods forbid we volunteer that we hired a professional to do something or did not live with some basket case situations while spending close to a decade weeding through problems in the most inefficient ways possible. this is not directed at everyone of course, and we all respect a person who does a workmanlike job with great savings and efficiency. it is a form of narcissism boring at best.
Well said.
Although I imagine someone else could have done it faster and with fewer words, albeit with 80% perfection and odds favoring rework sooner than later.
@Zray -- thanks, i use either Mobile 1 or Amsoil, both 0W-40 with no consumption either. the Champion Laboratories oil filter is excellent. this company supplies other brands and private labels. an inexpensive way of obtaining one is to purchase the Royal Purple 20-2009 Oil Filter, available on Amazon for USD $14.99 last checked. from cutting them open over the years it is obvious that one can use this filter for at least two oil changes and that it is very well made. FYI Honda started over ten years ago specifying that the oil filter was to be changed every other oil change while at the same time switching to a smaller filter. consequently one can use an even better filter and save money at the same time.
@Zray -- thanks, i use either Mobile 1 or Amsoil, both 0W-40 with no consumption either. the Champion Laboratories oil filter is excellent. this company supplies other brands and private labels........"
it bears pointing out that all of the Champion Lab oil filters which are made to be sold under other labels, like they do for the Mobil 1 filter line, are not all identical. Often the client directs Champion Labs to produce a filter to a certain set of specifications. And I suppose, just as often, the generic Champion Lab filter is merely relabeled as needed.
In the case of the Mobil 1 filter, made by Champion, there are some important differences.
1) the end plate is a unique design.
2) the can is thicker
3) synthetic fiber element, not plain paper as in the generic Champion
here is the link to the whole comparison article. It was likely a paper written by an ACC student, and is over 15 years old yet I wouldn't dismiss it out of hand as it still contains some interesting information and is still relevant.
@Zray -- thanks for posting the paper. have read it before and it is good to have it here for others. the fact that the client specifies how the filter is made is why i either purchase from Amsoil or RP. Amsoil does not have our filter size in their offerings. it is key that the filter media be synthetic with higher end oils and long term usage.
Low Oil Pressure Cold Start
