I know some don't put much stock in short interval UOAs, but I do this for fun/curiousity not money savings (my cars are my hobby). Anyway, this is my '66 Dodge Polara, rebuilt-in-2006 440 v8 with 18,000 miles, first run on an SM oil. Disregard the silicon- I'd replaced valve cover gaskets less than a month before putting in this fill of oil. I did a UOA on a short interval because I was a bit concerned about a number of things- fairly fresh engine, old engine design, fairly high power/hard use, use of SM oil with a semi-aggressive flat cam, etc. and the elevated iron might tend to back that up, but its also still a fairly new engine and gets driven hard. I'll track the iron and see, but I've taken the precaution of going back to SL oil (RP 5w30). I don't put much stock in how an engine "sounds and feels" but I do think its got a bit less NVH on the 5w30, and I like the way the oil pressures run much better. I no longer see peaks over 85 PSI at high RPM, but I still see 25+ psi at idle- right where I built this engine to run- its made for lighter oil than heavier. I liked the way it ran on RTS 5w40 and would have run it again except for the much higher pressures. Don't like that much loading on the oil pump drive. I'm sorely tempted to try it on a 0w20, but I want to track the iron for a while first and make sure its still trending down. Interesting how high the lead shows in the universal averages for the 440- wonder if that's a lot of samples with leftover contamination from leaded fuel? The other thing is that this is can serve as an almost-VOA for RP 0w40. Clearly its got more ZDDP than mainstream passcar SM rated oils, but I don't know that I like the fact that it doesn't seem to compensate for the lost ZDDP with a boost in moly or magnesium the way other SM oils seem to. Could be they're using a chemistry that doesn't show up on an elemental analysis, though. A lot of people say RP oils shear badly- this doesn't indicate much shearing to me. True, its a short interval but this engine should theoretically shred inferior VII packages: gear driven oil pump, high pressure/high volume oil pump that sends a lot of oil jetting turbulently through the pressure relief valve all the time, flat tappets, no rollers anywhere in the rocker train, and chain driven cam. I'll also hold out judgment on RP until I get a much longer run in on this load of 5w30. Anyway, this is analysis more a for-your-amusement (and for my information) than anything else. Any other insight/speculation welcome.