royal purple is an engine oil brand...made in the U.S.A,they are high qualities engine oil...suddenly until now i dont have the cahnce to buy it... :cry:
i'm using motul 5100 10w-40 now.its better than shell advance vsx that i used before.riding on long uphill is better and i'm gonna stick with motul i think.its a lil bit pricey but worth it.