Hello this is my first post for this forum and is not for my car. My brother is complaining about some problems with his 1990 GMC Sierra s-15 classic with a 4.3l v6. A big problem he was complaining about was the oil pressure gauge fluctuating from 20-80 while driving. The car has plenty of oil and it should still be fairly new and under 3000 miles. I have read that this could be normal but it does seem a little odd just in how much it moves. The larger problem is the new sound of the motor. The motor has completely changed in how it sounds. Suddenly it has a much deeper sound almost like it is missing a significant part of its exhaust. Yet the muffler was replaced a few years ago to what i believe from the cat back. Any suggestions would help. most importantly i would like to know if there is this is a major problem and is still drivable to me it seems ok but i would like a second opinion. Again its not my car so i will try my best to answer your questions. Thank you for your time.
