The vehicle: 1990 K1500 with 5.7L TBI 190K miles. I'd like to drain the oil in my old truck this weekend. It's been 2 years since I've drained it....about 20k miles. It burns about a quart every 600 miles. I change the oil filter (Napa Gold) every 5k miles. When I top off the oil (with at least a quart), it gets either new oil (usually Maxlife NextGen) or old oil that I drained from my Honda and/or Subaru (high end synthetic with about 5k miles on it....so plenty of life left in this used oil). Truck has a sludge issue when I purchased it 3 years ago. My idea, to help get rid of any more gunk, crusty, sludge, etc. is to drain the oil after a nice hard highway run, leaving the filter intact. Fill crankcase with 5-6 quarts of either A.) Kerosene or B.) 50/50 mix of Kerosene and Mineral spirits. Unhook wire from coil to distributor and crank truck over for several 15-20 second intervals in an attempt to circulate the solvent. Let solvent sit in pan for 30 minutes or so, and then drain. Install new filter and fresh oil. You guys see any problems with this type of "flush"? It's an old, tired, beat up, abused engine. If it dies tomorrow, I won't be surprised. But do you see this "flush" doing any damage? And no, I'm not real worried about the solvent breaking loose tons of crud and clogging up my oil pickup. I've run a few gallons of MMO through her for the past 30k miles.