Originally Posted By: tmundal
I had a vendor (who doesn't sell RP...he's our BG rep) telling me that Royal purple was the best synthetic out there...and WAY better than M1 and PP et al. Just curious what the consensus around here is?
Is it worth the extra price? I did a search, but there wasn't a whole lot of info..
The board seems really divided on RP- some folks hate it, some like it.
I'm totally neutral on it at the moment- I'm trying a run of RP SL-rated 5w30 in one of my slider-cam vintage cars and I'll see how that goes. I did a short 1000 mile run of their 0w40 (SM rated) in the same car, and it didn't show any of the shear-down that a lot of people say RP usually shows. It did have a bit more iron than I'd like- but then I don't have any other baseline for that engine yet so its just a single observation with no conclusion. All the other wear metals were below the averages for that type engine. I'll see if the iron trends down with the SL rated 5w30 and if so I'll run it longer and see how the viscosity and TBN hold up.
Personally, I can't see any reason to run RP in a newer car that will tolerate SM oils when Mobil, Valvoline, Pennzoil, and others make such a great array of modern SM synthetic oils that cost the same or less. For my purposes, RP is a way to stick with an SL oil for a specific engine and still have a wide variety of viscosities to choose from. I could also run Rotella T Synth for the cam protection like I do in the Jeep, but when I built the engine I was aiming for a 30-wt oil. 5w40 is just too thick and spikes the oil pressure too high at high RPM, and I'm sure limits flow rates to less than I'd prefer.
