For years I ran Mobil 1 5w30 in the 5.7L V-8 in my 98 chevy truck and my engine always seemed kind of noisy. When oil analysis determined I wasn't getting my money's worth with Mobil 1, I switched to Chevron/Havoline conventional oil and my engine was finally quiet. Mobil 1 was also noisier in our 98 Pontiac Grand Prix.
As for synthetics in the rearends, I don't use them. This same 98 chevy truck used Mobil 1 diff fluid from about 20,000 miles until around 75,000 when the pinion and carrier bearings had to be replaced because of excessive wear. I barely ever towed or carried anything in this truck and it was not abused at all. It might have just been coincidence but I quit using synthetics in the rear end. Conventional oil works fine for me and is all I use anymore.
Wayne
As for synthetics in the rearends, I don't use them. This same 98 chevy truck used Mobil 1 diff fluid from about 20,000 miles until around 75,000 when the pinion and carrier bearings had to be replaced because of excessive wear. I barely ever towed or carried anything in this truck and it was not abused at all. It might have just been coincidence but I quit using synthetics in the rear end. Conventional oil works fine for me and is all I use anymore.
Wayne
