My buddy did a analysis with Blackstone a while back after I suggested it to him. '94 Grand Cherokee with the 4.0 @ 140K. Evidently the store had only 3qts of PP and 4qts Mobil 0w-30. He was going for thin stuff but I don't think the 5w-20 helped. He did 3qts of PP and 3.25 of Mobil. This sample is from winter use here in Chicago, uses it mainly for work so it sees 50/50 city/highway with a lot of built up idle time. He's also a lead footed driver. About half minute warm up times when started from cold. ALUMINUM 5 CHROMIUM 2 IRON 65 COPPER 2 LEAD 3 MOLYBDENUM 69 POTASSIUM 2 BORON 35 SILICON 12 SODIUM 10 CALCIUM 2145 MAGNESIUM 13 PHOSPHORUS 620 ZINC 767 cSt Viscosity @ 100°C 9.02 SUS Viscosity @ 210°F 55.8 Flashpoint in °F 340 Fuel % 0.8 Antifreeze % 0.0 Water % 0.0 Insolubles % 0.3 No TBN Normally he runs a 5w-30 in winter and switches to a HDEO in the winter. Don't really have anything to compare it to since it is the first analysis but the iron is up there. I know the long idle times aren't helping but he needs the motor running in order to power some equipment on site.