I'm the original owner of a '97 4x4 5.9 liter gas. Its got about 175,000 miles on the original engine, tranny and all other major components. The truck runs like a top and I have done all my own oil changes every 2000-3000 miles sometimes with Amsoil synthetic, other times with good name brand non-synthetic. What concerns me a little is that my oil pressure guage goes toward the lower end of the normal zone now when idling or at low rpm and with a warm engine. Highway driving has the needle pointing straight up no matter what temp. I'm due for another oil change and was thinking of removing the pan for the first time to see if the pick-up is surrounded by sludge, etc. Truck has no oil leaks, nor do I want to create any. Can you guy see a dirty pick-up tube as my problem? Any other thoughts? Just ignore it?

 

if there's no irritating oil leaks to fix, i'd leave it alone. your lower oil pressure is probably due to bearing wear and increased clearances, which i'd say is normal for a high mileage engine. also, since your running synthetics, its unlikely that you have any sludge. and, dropping the pan, and even changing the oil pump, will probably not accomplish anything.

if you think you have sludge and just want to do something, consider a Gunk brand flush where you pour it in, idle for 10 minutes, and then change the oil. its a bottle of smelly solvent thats not supposed to hurt anything, other than dissolve sludge. its cheap.

 

The engine flush works good. I have used it before.