I have an 02 durango 4.7l it is fairly used (250,000km or 155,000 miles) when idling it has ok oil pressure for a high mileage vehicle. It is just above the second mark (\ l l /)
It's about ^ there!! When driving its
(\ l l /)
^ like there. I'm going to do an oil change right away (to check for sludge) how do I clean out the sludge if I got it?

 

I had an issue where my trucks Oil pressure gauge would drop to where yours is, when driving but usually when I came to a stop at like a traffic Light. I changed the oil and it stopped happening, I had no sludge(if you have maintained the vehicle I am guessing that you don't have sludge either) I would change the oil and make sure you put the right amount of oil in it. If that doesn't work I am guessing maybe oil pump or oil sending unit.

 

definitely try changing the oil first and see if that helps. Do the easy things first.

also, it is normal for the oil pressure to fluctuate some. As long as the needle is within the two inner marks you should be fine.

 

So lets get this straight. You are having normal oil pressure at idle and it is bottoming out when you start driving?

 

+1 that_guy

also, you cannot accurately diagnose sludge without pulling the engine apart (usually the valve covers off)

 

That was the first thing that came to my mind as well!......Doesn't make sense!


I would suggest the oil is the wrong viscosity so replace it with 5W-30 or you could even try 10w-30 and a new Bosch filter. I would also replace the oil pressure sending sensor.

 

Could also be a cracked / clogged oil pickup. At low RPM's there's enough of a draw but when they go up the pump starts to cavitate because it's either drawing air (crack in the pickup above the oil level) or a clogged screen is restricting flow.

Get the oil & filter changed asap. If possible, put a temporary mechanical gauge in place of the sensor to check your real pressure.

Bob

 

Oil sending unit or glogged pick up screen

 

Had the same issue with my first car when i was 17...turns out that i was 4 quarts low!!!

 

I agree with Old_School I had a 89 Astro Van, it had damn near NO oil in it. The oil stick only had one single drop of oil at the tip of it. lol.