Hi ya all, I'm new HERE. I am currently completing a rebuild of a 82 Dodge Mirada with a 85 360 4Bbl. All new bearing, rings and seals. I am installing TOTAL SEAL Gapples rings for thier extra sealing and reduced blowby. Every one I know states to use 15w40 Dino oil forever. Car Craft Magazine just did a bild up on a 318 and the base line oil was 15w40. Then they changed to Royal Purple 10w40 and got 9 more HP at 100 less RPM. This engine should put out 1 HP per cube. I will have an oil cooler also. So what to use? Any help is needed. Thanks, DaveJ