Wow, here's an old thread I started a few years ago....Anyhow, since then I've done more and more research on synthetic oils and additives, and I always look to use the best oil I can in my vehicles, in hopes that it really does make a difference as far as protecting my engine and prolonging engine life, because we all know I keep my vehicles forever, Lol.:lol
Anyway since I bought my '13 ram sport it has always had what's know as the "Hemi Tick" and it drove me absolutely crazy that a brand new vehicle always sounded like it had a lifter problem. Don't get me wrong I know a lot of the newer style engines have a slight tick, but these Hemi's are really bad. So in doing some research I came across some very interesting articles and info which lead me to an oil called Redline. From all the research I've done Redline and Motul are the only group 5 synthetic oils that can be had in these parts. Amsoil Signature Series is group 4 and Mobil, which used to be group 4 is now group 3, after taking some cost cutting measures to their process. The big thing with Redline is that is contains a high content of Moly which is essentially a friction modifier, and any engine guy will tell you that Moly is a key factor in protecting an engine. With my Ram, the Redline actually did take the "Hemi Tick" completely away, and once I change the oil I will be sending a sample of the drained Redline away for analysis to gain a bit more knowledge on this stuff. Here are a few links I think you will find helpfull, if this is something you're concerned with.

Five groups of base oil and Why Choose Synthetic Lubricants - klotzwarehouse, Synthetic lubricants warehouse, Racing oil, Fuels & Lube

Esters In Synthetic Lubricants - Bob is the Oil Guy - Bob is the Oil Guy

Wow good find! I'll have to check that stuff out! What group is royal purple considered in?

I believe RP is Group 4, and is a very good quality oil.

That's what I use now, but ill have to look into the price difference for this Redline Oil!