Redline. Have uesed it for years in many different applications. AMsoil only bests RL in its extreme long drain capabilities if anything. Other than that RL is actually much more superior and I would only consider it or Motul in a racing/heavy duty application where extended OCI's were not needed.
I`ve never tried RL,so I can`t compare the two. But,I use RP fairly often and my car`s engine really *likes* it. Runs silent,smooth,and responsive. My two fave oils are RP and Valvoline white bottle. If it were only one oil,it would be the Valvoline over any synthetic I`ve ever tried.
1 - Ignore the haters of RP on this site. Hating RP on BITOG is the "in thing" the "FAD of the month" thing. Go anywhere else in the automotive internet forum world and it is extremely popular and favorably commented on. Those comments are from people who have actally used it as well so you can take what is psted to heart. Overwhelming vast majority of negative comments about it here on BITOG are from folks who never used it by their own admission.
A lot of what is posted here is innaccurate as well such as it is Grp III( false = Grp IV PAO )and that this site has tons of bad UOA's which in fact it does not( another member bumped all UOA's on RP and OVERWHELMINGLY positive ). Take a lot of what you will read here about this and that bad aspect of RP with a grain of salt because most of it is false or just malicious, ill informed, rumor.
There have been a couple bad experiences with it( guy with a HEMI comes to mind= Gramps soemthing )but no more so than any other brand. Some oils do better in certain applications than others. All oils do that but only RP is trashed for not doing well? For some reason people here just hate it and apply one set of standards to RP and another set to other brands? It is really lame.
2 - In reality RP and Redline are 2 of the best oils on the market. Either one is a great choice. Both are top of the line premium oils. I personally use RP but have used and would use without hesitation Redline.
I do not hate RP, I am actually currently using RP ATF in few of my cars...i find it to be the best...and very happy it...also promoting via my signature....
Now, when it comes to engine oil's, I prefer Red Line over Royal Purple....i have never said that RP is a bad oil ever!
I have used both, so have my friends... I liked RL!
currently most of my cars have either GC or Mobil 1 EP in them with the exception of 1 car which has Mobil 1 ESP 5W-30 in it.
Just add purple dye to Red Line and enjoy the best of both oils.
Honestly, they've both worked for me in the past (RL 0w-30 and RP 0w-40). I would choose Red Line because I'm a snob and consider it higher technology. Also, that stupid purple unicorn that gets posted so often has turned me off of Royal Purple.