No, I do not use synthetic oil, but it is 5w30. I have 67k on my truck, and it has not had synthetic in it yet. Everything I have ever read has said not to switch on a higher mileage vehicle. I have used synthetic in vehicles I bought with fewer mileage on them, but still am not sold on the issue. (It is much more prone to leaks) My dads 01 (which he sold to a friend of mine) has had synthetic 5-30 in it since he hit 2500 miles. That truck still makes the same noise and has about 40k on it now.
Correct me if I am wrong on this, but I know for a fact that synthetic oil is 'thinner' than conventional motor oil. Yes, the viscosity is the same, but the chemicals in the synthetic and not as stongly bonded together as conventional. Take notice when you pour synthetic it splashes in the funnel and appears to be much thinner than pouring conventional oil. (I did a major project on motor oil viscosity in a chemistry class i took in college)
Back to my truck, the wierd part is that you dont hear it until you put the truck in gear. If I let it sit and warm up for 30 seconds or so before I take it out of 'Park', it doesnt do it, or I just cant hear it inside the truck.
huh, thats weird. Dont know what it could be then. I have used synthetic in mine since 2800 miles and so far *knock on wood* I dont have any leaks or other problems. Has anyone ever said just how many miles is too many to switch to a synthetic oil? I use to have a 93 chevy s10 that had 89,000 on it when I bought it and I swictched to synthetic and never had any probs. I sold it 3 years later with 143k.
Anywayz, good luck with ur truck and I hope u find that noise. Maybe it just likes to warm up before u take off. I let mine run for approx 5 mins regardless of the weather (hot or cold)