To quote a famous individual, C'mon, man! If somebody is so dim as to not immediately check the dipstick after seeing a pressure light, then he deserves whatever happens. Stupid should hurt. And I gave the OP far more credit than that when I wrote this.

 

Just to stray off topic for a moment, low oil level has zero to do with low oil pressure. I have run cars to below what the dipstick could detect and they maintained fine pressure. However, such a condition can easily cause the pump to ingest air instead of oil, causing a low pressure condition, if one was going up a steep hill, or driving in such a manner as to cause the oil in the sump to violently slosh around, just for example. The only way oil level affects oil pressure is if there is NO oil in the sump.

Now if, after having his oil changed, OP's garage forgot to put oil in the engine, OP would have immediately experienced an oil pressure light and the engine might possibly have seized. None of which happened, ruling out oil level as a potential cause of OP's complaint of wildly varying pressure readings. The symptoms point more to a pressure measurement problem, than to an oil starvation problem.

Happy 2025 to everybody here, and many thanks to those who make this board such a wonderful resource for those of us who drive around in these beautiful time bombs.

 

So you do accept that a low oil pressure light could be caused by a low oil level and therefore checking the dipstick is the best first response if one sees the oil light?

I wholeheartedly agree with you, which is why I found your phrase "There are a limited number of things that can cause low oil pressure, and oil level is not among them." so puzzling.

Richard

 

I would want to confirm that 0~20 wasn't used.
wj

 

No, 5-30 synthetic is used and the problem is sudden onset (immediately after an oil change) as well as being sporadic.

I'm taking my car in tomorrow to check the pan/sump and also the tensioners (which may be plastic, because I've never swapped them out).

 

I consider a "low oil level" condition to be completely separate from a "no oil" condition. The OP did not have a "no oil" condition or there would have been different symptoms. When I wrote the above I meant that simply being a couple of liters low will not, in and of itself, cause a low oil pressure condition.

I hope that clarifies things. I'll endeavor to be more clear in future postings.

 

No problem. I'm not sure who suggested that the OP might have a "no oil" condition but, as you say, the symptoms never fitted that explanation.

I never take any of my cars to a dealer as they are generally completely useless. However, I made an exception with my Wife's brand new 2018 Mazda, which we bought from a Mazda main dealer, as I wanted to preserve the guarantee so I took it back to the same Mazda main dealer for its first service. As soon as I arrived home, I let the engine cool down and then checked the dipstick. The oil was just visible on the very bottom edge of the dipstick, way below the minimum oil level mark. I phoned up the Service Manager and he could not believe it so I sent him a video of me fully inserting and then withdrawing the dipstick with a close up of the end.

He suggested bringing the car back but I refused as it was clearly not a wise move so he agreed that I should top up the oil myself and they would pay me compensation, which I was happy with.

Richard

 

Did you see the oil container or labeling?
wj

 

it was you , right ?

i believe your post (quoted above) asking, "..What oil pressure reading do you think you might see if you ran the engine with the oil level so low that there is no oil in the sump? ..." is what led many / some of us to think you were in essence saying an "oil level so low that there is no oil in the sump" equals "no oil". Thats what I took the statement to mean. After all, if no oil in the sump , then where is it ? . And why bring up a "no oil in sump" question if if didn't apply to the OP ?


Richard, I truly believe our communications are hampered by our different interpretations of the almost common English language we speak. And in no way impinge upon the hard earned knowledge we each have accumulated

Z

 

My observation about no oil equating to no pressure was to illustrate to Y2KJag that he is incorrect and that there is an undeniable relationship between oil pressure and the level of oil in the sump, such that, in extremis, zero oil equals zero pressure. One can, of course, extrapolate qualitatively from this extreme position.

At no point have I even hinted that the OP's problem, which is occasional low pressure at idle, could possibly be caused by having no oil in the sump. As Y2KJag states, the symptoms of having zero oil would be totally different.

I find it difficult to understand how my words can be interpreted in any other way, but, as it happens, Y2KJag has now revised his original statement so all is well with the world.

Richard

 

Unless you fit a real oil pressure gauge you know nothing . I run 15 w40 not 5wDumass

 

Which is really the only way to determine if it's the oil pressure sender (switch) or the actual oil pressure that is causing the problem. Given how cheap a new sender is, I think I would have immediately fitted a new one to see what the result was. No doubt that has already been suggested somewhere in this thread, lost amongst the debate about what constitutes no oil or low oil, comments about the battery and what brand and spec oil is best (personally I use Castrol Titanium Edge Magnatec 5000 GTZXSPECTRUM and change it every 100 miles).

 

The 2024 OP himself suggests fitting a new pressure sender and I reply by suggesting that the actual oil pressure should be measured so it looks like the first two posts covered the lot.

Richard

 

Change oil every 100 miles ...??? More expensive than the petrol.!!

 

It's the only way to be sure you don't have low oil pressure.

 

I missed that - probably because the OP tacked his question on to a 10 year old thread. The thread can now be closed until the next update in 10 years time. 😛

 

You too??

 

Good call.
My uncle Clive used to put that in his C5.

Swore by it.

 

I'd also swear a lot if I was changing the oil every 100 miles.

The original Jaguar recommended oil for the XK8 was a mineral oil so you can safely double the recommended oil change interval by switching to a good quality fully synthetic oil, as I have done for the last 27 years. Reducing it to 100 miles, assuming that is not a typo, is very left-field.

Richard