API certified means the oil meets the specs in your manual. The current API certification is API SN and the current ILSAC specification is GF5. This is in your manual as well.
For cars under warranty, it's best to use an oil that meets these specifications. But when you turn up the wick, it's best to look into an oil that can handle it.
Before switching to a higher grade (weight) oil, I would use a more robust xW-20. RP forumulates their HPS oils with a little more ZDDP, their proprietary Synerlec additive, and non-API oils are also usually a little thicker than API oils. The number on the bottle doesn't actually tell you the viscosity since that number represents a viscosity range.
Quote:
Royal Purple HPS Series motor oil is specifically formulated to maximize performance and meet the demands of high performance and modified engines. HPS is recommended for vehicles no longer under manufacturer warranty and for those seeking a higher level of performance and protection.
This unique blend enables HPS to outperform leading synthetics and conventional lubricants for both gasoline and diesel engines. Royal Purple’s HPS is fortified with a high level of zinc/phosphorus anti-wear additive and Royal Purple’s proprietary SynerlecŪ additive technology.
|
If you look up the API certified RP 5W-30 oil, it tells you that it meets the fuel economy requirements of a 20 grade oil. I would go with a xW-20 oil with a more robust additive package (like RP HPS 5W-20) over bumping up to a 5W-30.
Quote:
A low coefficient of friction results in optimized fuel efficiency (the fuel economy of our 5W-30 meets the fuel economy requirements of a 5W-20 oil)...
...For those seeking enhanced performance in vehicles not under warranty, we recommend our HPS Series of high performance street motor oils with our proprietary Synerlec additive technology.
|
-Dennis