Does Royal Purple maintain its purple color after it’s put into service?August 17, 2018
Can your oil be used with flat tappet cams?August 17, 2018
Yes. All Royal Purple® engine oils contain the zinc/phosphorus compound zinc dialkyl dithiophosphate (ZDDP), but the maximum amounts are restricted by the current API oil specifications. For stock, non-performance automotive street applications, API SN licensed oils are OK. For better wear protection, Royal Purple HPS and XPR lines of engine oils are formulated with a higher concentration of the zinc and phosphorus anti-wear additive and are suitable for ALL flat tappet and roller tappet camshaft valve trains. For a specific recommendation, contact our tech department at 888-382-6300.