I try to keep an open mind about oil instead of being loyal to one brand. I've also been on bobistheoilguy for a long time so I tune in closely there to the people that actually work in the oil industry (although there are only a few left) instead of the people that think that looking at a product data sheet, or buying oil only from Wal-Mart, is the best way to choose oil.
IMO, none of the oils that I've mentioned will hurt the engine unless you have a problem (like burning a quart every 500 miles). Red Line and the old Motul 300V have lots of phosphorus which has been reduced in current oils for fear of cat poisoning.
http://www.gf-5.com/the_story/performance/
IMO (notice how I use IMO a lot), you would have to be burning a
lot of oil for it to get to your cats to do harm. One of the guys in the oil industry at bitog has been using diesel oil in cars since the 1960's! After years and years of blown turbos and spun bearings at nasioc, more and more people are running oils that are not Resource Conserving GF5 or GF4 oils and are having less problems these days. Almost every time someone has a problem it is from using a GF5 oil on a modified car. No dead cat threads there!
Ideally, you want an oil thin enough to properly lubricate the engine, not cause excessive drag, has a good anti-wear additive package, and provide decent fuel economy. I think Royal Purple's
marketing is crap. They take a machine used to test Extreme Pressure additives in gear oils and test their engine oils and everyone thinks it's great oil. Their old 5W-30 is known to shear badly even in moderate conditions. All of their oils have been reformulated though and some of the GF5 oils of all brands are showing pretty impressive results, although I'm still leery of using them in a modified turbo car that specs 5W-30.
GC is popular because it stays in grade, meets European ACEA A3 specs for shear stability, is usually found at Autozone, is a robust 30 weight for folks that don't want a 40 weight, and turns out very good uoa results in various conditions. It also meets the old API SL specs so it has higher amounts of anti-wear additives like zinc and phosphorus.
Mobil1 0W-40 has slightly higher levels of anti-wear additives than GC, but it could be overly thick if you have stock internals. Amsoil oils are very good and a lot of people hate them for the way they do business and you can't buy it at Wal-Mart. Amsoil Series 3000 HDD 5W-30 has shown good uoa results in WRX's and is a robust 30 weight with higher zinc and phosphorus levels than Rotella!
The problem with a new car is that there isn't a lot of data out there so you guys are pretty much pioneers.
On stock internals with FI, I would probably run one of the following and do a used oil analysis at around 4-5k miles to see how it's holding up:
- 2 quarts of Motul 300V 0W-20 with the rest Motul Eco-lite 0W-20.
- 100% Red Line 0W-20 or 5W-20 (RL 5W-20 will behave more like a robust 30 weight with it's high High Temp High Shear).
- 2 quarts of Amsoil Dominator 5W-20 topped up with Amsoil ALM 5W-20. (Amsoil Dominator has more ZDDP than Rotella)
- GC 0W-30
- And MPT has a crazy high additive package as well (but no 20 weight).
http://matrixsyntheticoils.com/store...reet_oils.html
I would probably lean more towards a 20 weight on stock internals. You just don't have a lot of choice with robust 20 weights. I've run very thick 40 weights and very thin 30 weights* and the only oils that I really noticed a subjective difference with are Red Line and Motul 300V.
*Motul Eco-nergy 5W-30 API SL
Motul X-clean 5W-30 API SM
Motul 300V 0W-40 No API
Red Line 5W-30
GC API SL
Mobil1 10W-30 High Mileage API SL
Mobil1 0W-40 API SM and SN
Pennzoil Ultra 5W-40 API (I forget)
Amsoil DEO 5W-40 API SM(?)
Amsoil SSO 0W-30 (No API)
Mobil1 5W-30 (old API SL version)
Hope this doesn't confuse you more.
-Dennis