The Stovebolt Site Forums The Shop Area Engine Shop oil pressure question

Hi guys,

This question, while pertinent to our old trucks, actually has to do with a newer vehicle on which I need some advice. I have a 99 jeep with 150,000 miles. I've changed oil religiously every 3,000 miles. On my last change, I went from 5-30 (I live in a very cold climate) to 10-30, since spring is eventually coming and the temps are rising. Before changing, the running pressure was registering at about 40-50 lbs, with idle at about 25-35. Now after this recent change I'm running at first at 80 lbs then settling in at about 60, with idle at about 45-50. It's still fairly chilly here (20s), but can the change in weight have that much effect? I've never seen anything that dramatic on this vehicle? If not, what's going on? Any advice would be greatly appreciated. I'm worried that something severe might happen.

Thanks,
Jim

Yes, the heavier weight oil will raise the pressure that much. No, it's not really a problem. My Explorer started losing a little pressure at idle when it got to about 100,000 miles, so I changed from 10W30 to 15W40 diesel-rated oil. Since I buy it 5 gallons at a time for my farm tractor, it's more convenient to run all our vehicles on the same oil anyway. Engines that run 5W30 oil when new will develop enough wear in 100,000 miles or more to use the heavier oil effectively, but don't do it on a new engine with tight clearances.
Jerry