Ok anyone a "Oil Tech person" translate or even find spec sheets that might compare the two oils. The Mobil 1 15w-50 is under the SCCA program on decent pricing plus most of the Auto parts stores aren't carrying 15-50. The Idemitsu is available in 10-30 or 20-50 which I would tend to favor. Maybe with a little luck we will be able to run long enogh to need to change oil!!!