Motorhome has a 1990 460 V8 which specs oil pressure of 40-65 psi at 2000 rpm hot. I was running a cheapo gauge (by “Make Waves Instrument Corp”) and it read 58 psi hot at 2000 (30 psi idle). I obtained a Sun brand gauge and installed it instead of the cheapo. The sun shows 70 psi hot at 2000 (40 psi idle). I am more inclined to believe the Sun gauge. Anyway, that pressure is above the spec range, so my scheme is to get some HDMO 10w oil to mix in the my crankcase and slightly thin the oil. It takes 6 quarts, so 5 quarts 10w30 with one 10w should net me (I believe the NAPA 10w is 6 cSt) about a 9.5 cSt or a borderline 10w30. What do you think? Probably won’t see much drop in op at a reduction of 1 cSt. Two qts 10w would get down to around 8.1 cSt, which probably is too low.