1997 Isuzu Trooper Limited 140,000 miles.

I've owned it since 2000 and ever since then it has had a manageable oil pressure issue. When the oil starts to break down the Trooper starts making the tell tale ticking noise to let you know it is time for an oil change. After the oil change everything is fine. Oil pressure runs a hair under 85 at 3,000 rpms.

This is the way it has been since it had only 30,000 miles on it. I've put on about 100,000 miles since then. My mechanic always said just let it be and do the frequent oil changes. Lately I've started wondering if all of these years we should have at least dropped the pan and at checked for screen blockage. Since he has not explored the pressure issue I assume he thinks it's something big like bearings or pump. He has never said.

The oil pressure is now running a little lower, even after oil changes it's around 79 at 3,000 rpms. I'm concerned it is now starving the oil system and doing more damage.

I guess my question is, should I try something like SeaFoam in the oil to clean everything up? Some have told me not to because if it is a bearing issue it could cause a worse pressure issue by removing carbon and gunk that is actually helping to seal and improve the pressure. Or worse that it could release carbon and gunk that will block the screen and starve the system even more.

Any help is greatly appreciated!

Thank you!

Tim