Low oil pressure XJ40 (XJ Gold)

[harbaz]

Very recently I have had a problem after only a short trip but with water temperature normal, of the oil pressure dropping on tickover, a couple of occasions oil warning light coming on. The normal oil pressure is just under the "4" dropping only slightly on tickover. Engine sounds fine. I would have thought when the oil warning light came on I would have heard a knocking sound. Could it be the gauge? or what else may it be.
Vehicle is 1994 XJ6 Gold 3.2 140000 miles - uses no oil, just a puff of smoke on start up

[eb96pfh]

The oil pressure guages on these cars are not very accurate... its very unlikely to be suffering from genuine low oil pressure, although its always worth checking - most garages will be able to attach a genuine pressure guage to the thread in the side of the block and check.
Jaguar provide different sender units for replacements to these guages and these are more reliable (and work in a slightly more basic way). They are easy enough to fit as long as you have long enough arms to reach under the inlet manifold...

[strathmore22]

I have had the same trouble throughout my 3 year ownership of my 3.6. The oil pressure sender is the usual cause of this, I am told, but I replaced mine with another (2/h) one and it is still the same. I changed to a thicker grade of oil last time and this has made it better, but it still falls very low on hot tickover. Since nothing drastic has happened in all this time I am going to ignore it. Regards, Roger.

[phirou]

Very recently I have had a problem after only a short trip but with water temperature normal, of the oil pressure dropping on tickover, a couple of occasions oil warning light coming on. The normal oil pressure is just under the "4" dropping only slightly on tickover. Engine sounds fine. I would have thought when the oil warning light came on I would have heard a knocking sound. Could it be the gauge? or what else may it be.
Vehicle is 1994 XJ6 Gold 3.2 140000 miles - uses no oil, just a puff of smoke on start up

I experienced the same problem. I have been told that this was fairly common on many AJ6's, especially in summer or in a hot climate. Before trying anything else, try using 15W-50 oil instead of 10W-40. It should cure the low pressure at idle.
.

[phirou]

I have just done 500 miles, including some time spent in traffic congestions. We had a wonderful weather in central France last week-end, with temperatures reaching 78-80° F. Oil pressure was OK at tickover. When I was using 10W40, under similar circumstances, it would drop below the red line . My XJ40 (perhaps not all?) works much better with 15W50.