I was gonna post this in the Boat forum but figured more answers could be had here. I was thinking about running Schaeffer's 15W-40 PAO Blend this summer but am welcome to other idea's as to what oil to use. Boat is used primarily for cruising and oil temp stays 180-195 degrees. At WOT temps rise to 210-220 degrees but never over 230 deg. Oil Ideas? M1 15W-50 Schaeffer 15W-40 Blend Amsoil 15W-40 Marine Here are some specs on the Engine.... Oil Cooler @ Powersteering Cooler 5.7L 4 bolt Main Block Bored .60 over to 360CI Melling HiFlow Oil Pump Lunati Forged Crank Lunati Forged Rods JE Forged Pistons 224/224 .480/.480 112LSA Cam AFR 195 Aluminum Heads 2.02I 1.60E 10.2-1 Comp Lunati 1.450" Dual Valve Springs Edelrock Performer RPM Intake Lunati Gold Race Forged 1.6R Roller Rockers Lunati Custom Length Hardened Chromoly Pushrods Holley 750 cfm Double Pumper Carb Full MSD Ignition Engine Dyno was 424.5 Hp @ 441.3 tq BTW My previous motor in this boat saw many 150 HP Nitrous shots and after 10 seconds of spraying my oil temp would rise from 205-210 to 280+ and take a good half hour of cruising to drop down to normal range. Nitrous is very hard on motors and builds extreme heat as shown in the increase in oil temp in 10 secs.