I have a customer with a 1500 powered by a 5.3 whos been using Semi-Synthetic oil with Lucas and I just had him swap to a full Synthetic oil with Lucas and after a road trip of about 1.100 miles hes coing back in hes gotten about 72K on the truck anyone heard of anything similar?I saw a lot of soot in the exhaust pipes but no signs of leaking and this is the first time I have heard of any such thing.
I have read about similar issues in the C5 Corvette on the various Vette forums I participate in. Many synthetics run at the low end of the viscosity range for the applicable weight rating (e.g. 30 weight) and the oil apparently gets by the rings and is burned in the combustion chamber. Switching to a heavier oil, or one with a different basestock may have different results. I don't know what basestock Lucas uses, sorry.
