The reason you will find so few Royal Purple fans here on BITOG, is twofold:
1) Most here don't like to waste money where there is no return. We love preserving our cars. If you look at the signature lines, you will note that most here have a stable full of well preserved cars. We don't mind spending money, but not unnecessarily.
2) Most here tend to make decisions based upon evidence. Thus the interest in UOA, and the constant posting of studies, product data sheets, and professional articles. After dozens of threads on the subject of Royal Purple, no one has ever provided any evidence that Royal Purple provides any better fuel economy, keeps an engine any cleaner, or reduces wear, or that an engine ran on Royal Purple lasts any longer. None. Never. Sure, there are some nice anecdotal stories about how great it is, but no real evidence.
I've done a lot of research on what motor oil is used in high mileage engines, particularly cars that are reported to have made the million mile mark. So far I've only been able to find two that have reported the motor oil used.
First is a 1990 BMW that was ran on a treadmill. It got an exclusive diet of Mobil 1 and Mobil gas. After going 1 million miles, the engine was tore down and carefully studies. The tear down revealed almost no wear to the engine components. Almost all were still within factory specifications.
Second is a 1966 Volvo that has rolled over the 3 million mile mark. The owner reports that he has exclusively used Castrol products in it. When it was new, it came with a factory fill of Castrol. He stayed with that until 1968 when Castrol GTX was introduced, and he has used Castrol GTX in the crankcase ever since.
https://www.youtube.com/watch?v=gHmMlU8Q-V8
http://www.prnewswire.com/news-releases/...-300052313.html
Right now Castrol GTX is $16 - $17.50 for a 5 qt. jug at Walmart. Mobil 1 is under $23, and regularly offers a $10 - $12 rebate. So, if there is hard evidence that an engine can go a million miles, or even more than 3 million miles, on a non-premium motor oil, and there is no evidence of any other benefit such as fuel economy, then why spend the money on a premium priced product?
I've used RP. In fact RPHM is in the crankcase of my Outback right now, and I still have another jug on the shelf, right alongside two jugs of Mobil 1 AFE and a jug of Pennzoil Platinum. The only reason it is there is I was able to get it for $15/ 5 qt. jug when Walmart was closing out RP 0W-20. For only a couple dollars more than what I normally pay for M1 and PP, I was willing to give it a try.
So far it has proven to be a good motor oil. UOA reports show that it is close to equivalent quality to the other products I've used. Actually, I just looked at my UOA file, and the two highest iron wears (22 and 14 ppm) that I have had, both occurred while I was running RP. The lowest have occurred while running Castrol Edge and RP (both 8 ppm). And the highest viscosity I have seen, although still in spec, was a RP fill. All except the 14 ppm/high viscosity fill were 7.5k oil change intervals. The 14ppm /high viscosity oil change was a 8.4k mile oci.
Would I buy it again? Sure, if I can get it for $15 or less per 5 qt. But would I pay a premium for it? Not unless someone can show me some evidence that there is a benefit, other than making my wallet lighter.
