In the engines that foamed, 4500 rpm was well below the converter's stall rpm. These engines live at 7000-9500 rpm with dry sump oil systems. There's a sight hole in the oil reservoir. After about 15 seconds of sustained 9000 rpm, it looked like a whipped latte in there.
Originally Posted by FordCapriDriver
They sure wouldn't be risking openly recommending one specific oil for a certain application if they didn't believe it was a good choice. Perhaps on paper things may suggest that HDEOs can foam at sustained high revs. But i have never seen foaming with HDEO personally, i sometimes go out for a spirited drive in my Escort up the mountains, this usually means about half an hour ish of sustained 3000-4500rpm. I remember having read something about foaming with HDEOs and wanted to see for myself if the oil would foam. I shut the engine off after about half an hour of fairly high sustained revs and checked the dipstick, no foaming i could see.
Originally Posted by Building3
i just finished watching a video on the Hagerty website about Shell motor oils. Sure it was an infomercial. It was moderated by Hagerty with two Shell engineers. The engineers were adamant that Rotella T-4 15w-40 was the best oil for older cars with flat tappets, muscle cars, etc. Sure they are biased but why would they tell customers to use their HDEO in passenger car engines with flat tappets if it would harm the engines? They could have just said that they did not make oils for cars that old.