Concerning the Supertech Wal-Mart oil, I personnally contacted the corporate buyer at Wal-Mart to ask who supplied their oil. The answer is Quaker State. You can judge for yourself, but I ran this stuff for 197000 miles in a 4.3 L Chevy engine. At 130000 miles I changed the timing chain and gearset, and there was practically no sludge. At 197000 miles the engine was still not burning any oil, though the compression was starting to fall off. Like I said, judge for yourself, but I've never had any trouble with the stuff.