1994 Ford F-150, Oil Sludge Problem

Is this the inline six cylinder?

Is the pvc system functioning normally?

What brand of oil are you using?

What are your driving habits, do you drive short distances frequently (not allowing the engine to reach operating temperature)?

It is a 5.0 liter, V8, using 10W30 Motor Oil, Fram Filters, PCV systems functioning normally, usually drive until the engine reaches operating temperature, sometimes short trips.

My problem is that my oil pressure gauge reads low side of normal, but once in awhile it will move to center of normal, engine runs great, get good mileage for a truck with 115000 miles. I believe the low pressure indicator is due to sludge, because that is what I have learned thru some research. Just looking for a way to clean it out without having to take the oil pan off of the motor. Hope this give you enough information, thank you for your response.