I had it backwards, thinking 504 for a shorter (6mo) interval, and full SAPS for a longer interval of 12mo.
I don't think we fully understand the implications of the two different formulas. Heck, VW's sticker under the hood even lists these 2 vastly different oils; 502 and 504.
I would DEFINITELY use 504 over a specific 502 oil, like Syntec 5w-40, but oils that also have 229.5 full SAPS might have advantage over 504, stress on the "might". Of course, fuel quality being the decider in some cases.
Since I have a ton of Rotella 5w-40 already, and a bunch of PZ Ultra 0w-40 Viper spec I will choose to use it up verses buying 504 oil. However, if I was buying oil it would not be $50/jug 504, but rather half price PZ Euro L MB 229.51....one of the few products yo get more than your money's worth.
I have about 15G of CK4 RTS, and about 45q of PZ 0w-40, plus a few jugs of M1 0w-40 for my new Mercedes and 4 jugs of Rotella Gas Truck 5w-30 which will be the winter oil for the VW in a few years. Factory fill is only 10cSt, Rotella GT might be a lil thicker. It has a lightweight additive formula, which can only be an improvement on the current high calcium formulas. Even Edge 0w-40 went back to high Ca.
But yeah, I mixed RTS and PZ Platinum in my V6 DI Audi 3.2 for a decently long oci, and it did very well. Would people use these oil or a mix of them if they were free? I already have a stash, so yeah..... just a matter of selecting the best way to use them.
I am a winter/summer oil guy. My wife's commute is just a few miles at low speed. In winter her car barely warms up. Instead of 6 months / 6 months, I might even reduce it to 5 months of winter and 7 of summer. Timed intervals are where it is at!!!
I think you wanted to put here "I."