Originally Posted by dnewton3
If normal OCIs are your plan, I would recommend a 10w-30 HDEO. Perhaps T5, as it is very easy to get and very cost effective if you run it long enough.
But ...
Given your description of averaging perhaps 7k miles a month, that approaches 85k miles a year. I would HIGHLY recommend considering a good synthetic lube and bypass filtration, and add a sample port such as the Fumoto valve or other ball valve on an oil port. That way you can sample your oil and have it analyzed, and maximize your O/FCIs. Anyone who drives that much is a candidate for such investments, because a well-mamanged plan can pay you back big time, but ONLY if you manage it properly. This is not a system that is cost effective if you try to guess your way into an OCI; it must be tracked and managed. The 454 does not have a large sump, so the cost of UOAs will play into the whole fiscal consideration as well as initial system costs and also additional maintenance costs. It's not an approach for the lazy or quick-to-wrench; it's a method of saving money by overall management of the entire maintenance plan. If you choose this, then either a true PAO 5w-30 or 10w-30 would do well, and HDEO would not really be a necessity.
+1 more. Really good oil and by-pass filter. Run longer filter on stock mount to add total volume of oil - I'd suggest Napa Gold.
Do a UOA at 5,000 miles and see what it looks like? Do it again at 10,000... I'd guess it will be stellar unless you have a leaky intake manifold, bad air cleaner or something ... As long as the oil test OK, leave it be. With that many miles there will be little cold idle time. You have an ECU and O2 sensors to keep the mixture in check. I'd run a 190* T stat. 2 1/2 dual exhaust with full sized crossover pipe. You will be running some RPM's, so it needs to breath.
OK, so BBC engines can stand some timing, like 48~52* total timing at 4,500 rpm if not at full throttle (what it will stand for total timing is vacuum dependent, the more vacuum - part throttle - the more timing it'll handle). Fuel mileage comes with the most timing that the engine can live with.
Your ECU may not let you get all the timing the engine can stand, so have to look into that... Does it have the dreaded ECU controlled HEI? The answer to that question will tell us where you go from there for mileage gains ...