I use to have an International PU years ago that had a 392V8 that was pretty noisy. I used STP oil treatment and it did seem to help a little in real hot weather. but, not enough to really convince me from using it on other vehicles.

Doop <
76 F-100 Custom (96K Original North Dakota miles) 360-C6 All stock

64 F-250 (Bought from the north slope of Alaska) 292-T18 4 speed