A bit interesting that Amsoil, "First in Synthetics", recommends using GRP III (highly processed mineral oils) in RX-8 engines over its PAO (GRP IV base stock) products.

They label this XL series as synthetic, but it's base stock was allowed to be called synthetic legally after (Mobil vs. Castrol) in the legal synthetic moniker case where Castrol ultimately prevailed (Mobil objected to Castrol labeling Syntec (GRP III base) "synthetic").

http://www.amsoil.com/dealer/techser...a%20Rotary.pdf

Additionally, note that they recommend the 5W-20 as that oil is required to be low ash in order to meet standards.

 

rofl

of course, like u said, its a gp III oil, but labeled as Synthetic AND selling at Synthetic's price = more profit.

lol @ 5w-20.

 

Well, I've no idea whether to agree or disagree with Amsoil's position. However assuming they recommend XL over their PAO products for profit motive is cynical at best.

BTW, how has that thick oil done for your engine? Now an honest answer to that question might be funny enough for an "rofl"

 

I have been just waiting for someone to post the other side of the "Unless you are in cold climates" caveat that every oil threat mentions when promoting thicker than 5w-20. I do live in a cold climate, and I don't know if 5w-20 makes the grade because of that or not.

 

Hmm, good question. But lets attempt to derive facts from anecdotal evidence.

First, engine failure modes: Seems failures are generally related to apex seal wear/failure due to either insufficient lubrication and/or carbon deposit formation. What impact, positive or negative, would using a higher than recommended viscosity have on these failure modes? My opinion, which is shallow at best. None whatsoever.

Next?

 

FFS, like we need another thread about this. These posts should all be moved here https://www.rx8club.com/series-i-tech-garage-22/cumulative-synthetic-oil-discussion-52856/ and this thread should be deleted.

People are going to believe whatever the hell they want about this issue, so there's no point in debating it. It's been done to death already with little in the way of valid hypotheses or objective testing, just people ranting and repeating crap they've heard with absolutely nothing to back it up.

 

Oh no oil debate

Poster #1: I use I use 10w-30 synthetic for 10+ years now with no problems!!!
Poster #2: Well I used non-syn 5w-20 for 20+ years b/c thats what the manual/sevice tech said and my car has never benn better!!1
Poster #1: Well my oil is better
Poster #2: no MY oil is better!!!
Poster #1: no MINE!!!111!!!

 

Yes, people often quote things they read or heard as if they did the research. Yes they are going to believe what they want.

However there is new, at least to me, information on 5w-20 oils being required to have less deposit forming additives. People can use that information as they see fit, including dismissing it outright.

 

5w30 castrol here bc its cheap and i have 58k of warranty left.
20w is too thin and just used for US mpg ratings