I have a 2005 Nissan Pathfinder that has 79,896 miles on it. I have done a lot of warranty repair to the car (transmission, radiator, oil leaks and other fun stuff). My latest problem is when the car is running for more that 20 minutes and I slow down or press on the brakes my oil pressure gauge drops to L. I have taken it to two dealers one – said that the 'pressure was in normal range" and could not do a thing and the other fixed a leak in the oil cooler and replaced the seals behind the manifold. This still has not fixed the problem. At this point they feel there is nothing else they can do but this is not normal. Any suggestions? Besides selling it…
The problem might be with the oil pressure sending unit for the gauge.
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Tester
I believe that has been replaced and the issue is still not fixed. Any other ideas?
Then what is done is install a mechanical oil pressure gauge in place of the sending unit and see what the actual oil pressure is.
Tester
According to both dealers the pressure is within “normal” limits. Basically telling me there is nothing wrong. Very frustrating
How long did they let the engine idle with the mechanical oil pressure gauge connected?
Sometimes it can take up to a half hour of the engine idling before an oil pressure issue is revealed.
Tester
You car is 9 years old and has a few miles on it…It IS normal for oil pressure to fall off to a low level when hot and idling. 10 or 15 PSI is quite normal as long as pressure increases as RPM increase. What viscosity motor oil are you using? If it’s 5w-20, you might switch to 10-30 during the summer months and see if that improves things…
Also, you could take the vehicle to an independent mechanic and ask that they measure and record the oil pressure with a temporarily installed pressure gauge at idle, 1000, 1500, 2000, 3000 RPM… Minimum pressure at those RPM points would be 10, 15, 25, 35, 40 PSI . These are minimum safe pressures, another 10 or 20 pounds would be better…Expect to pay $50-$100 for this service…
Thank you I will try this and see if these suggestions resolve the problem.