First one is a myth, lots of myths in the oil world. And so is the second one. Here we go:
Royal Purple is a "boutique" oil in that it's a Group IV & Group V blend of PAO and ester base stocks. Their consumer line of motor oil is API certified to SL specifications, with the exception of the 20W-50 which is a SJ spec...their XPR racing line is not API/ILSAC certified. In addition, the 5W-20, 5W-30, and 10W-30 are rated API energy conserving. I do not recommend you use the XPR line in a street car...it lacks many of the additives you want in a daily driven machine. In this case, "racing" is not better
Royal Purple oils are more slanted toward the hi-performance/racing crowd in general and as a result, the additive pack contains less detergents and anti-oxidants than what you will see in German Castrol or Redline. Unless you do oil analysis, a 5000 mile change interval will keep the oil from degrading to the point where it's not doing it's job....IMO, a 8000 mile OCI would be safe for this oil if city driving is what you primarily do. The filter will need to be changed at the 4000 mile point for an 8K OCI.
Royal Purple's color comes from dye used in the formulation; German Castrol was green a couple of years ago (elves?) for the same reason. All oils (including syn oils) are refined clear...dye is added for marketing. Moly comes in two forms (maybe more)...inorganic MoS2 which must be in a carrier (suspension) to flow and an organic type which is soluble in oil. Royal Purple uses the organic moly as a friction modifier and actually contains less organic moly than Redline does. This type of moly will not clog up your filter.
I would like to point out something you will see on oil data sheets that's fairly common concerning viscosity:
Royal Purple 5W-30
40 deg C - 65.3 centistrokes
100 deg C - 11.0 centistrokes
Royal Purple 10W-30
40 deg C - 70.3 centistrokes
100 deg C - 10.7 centistrokes
The 5W oil is a bit thinner than the 10W at cold temps as expected, but the 5W is actually thicker than the 10W at operating temp. This is due to the friction modifiers used in the oil and illustrates another point: Oil never thickens up when hot, it always thins to the SAE viscosity spec shown in the 2nd number on the API stamp.
Auto and manual transmission oils live a much easier life than motor oil...they do not have to deal with combustion by-products. As a result, most will perform very well. Royal Purple's manual transmission oil is excellent...most syn oils of this type are. Redline is another excellent choice.
Auto tranny oil is actually hydraulic oil. The #1 killer is heat....all of them (DEXRON III spec) will perform well if you have a good cooler. Adding a transmission filter pre-cooler is also a very good idea, as is a temp gauge. Royal Purple, Redline, Castrol, and Valvoline are excellent choices.
Royal Purple 80W-90 and Redline 75W-90 LSD oils work very well in a LSD that's in good shape. Keep in mind, both contain the friction modifiers necessary for the LSD...Redline 75W-90 NS does not have the modifiers. However, if the LSD has a lot of wear, either of these syn LSD oils may cause excessive slip. In this case, the Ford 75W-90 may be a better choice...you will also need the Ford friction modifier.
Royal Purple Consumer Products
Royal Purple Consumer Products
Royal Purple Consumer Products
Royal Purple Consumer Products
Royal Purple Consumer Products
Now saving the best for last. Personally I use Nippon Eneos 0w50 now in my race Surpa:
Quality grade RG/API SM
SAE viscosity grade 0W-50
Appearance Orange
Density (15°C), g/cm3 0.847
Flash point (COC), °C 232
Kinematic viscosity (40°C), mm2/s 104
(100°C), mm2/s 18.0
Viscosity index 192
Pour point, °C –45.0
TAN, mgKOH/g 2.3
TBN (HCl), mgKOH/g 6.4
Color (ASTM) L3.0
here is the MSDS,
http://www.eneos.us/documents/MSDS_0W50.pdf
Unfortunately there is no data for some parameters i would like to know. I'll work on getting an oil sample of my used oil.
I was able to dig up a virgin oil analysis (VAO) done on the Eneos 0W-50:
Aluminum:1
Chromium:0
Iron:1
Copper:0
Lead:0
Tin:0
Molybdenum:42
Nickel:0
Manganese:0
Silver:0
Titanium:0
Potassium:2
Boron:59
Silicon:3
Sodium:7
Calcium:1811
Magnesium:20
Phosphorus:662
Zinc:790
Barium:0
SuS @210*F: 85.2
Flashpoint *F: 425
TBN: 8.5
It appears the 0W-50 is a PAO base stock with ester added as a seal conditioner. The add pack seems a bit light for a street driven car...though, the TBN was higher than the advertised 6.4. This oil is thinner than the other 50W multigrades on the market, meaning it will flow better, but not near as well as a 0W or 5W-30. Could be due to Eneos' focus on racing (like Royal Purple)...this oil does not look well suited to extended drain intervals, but should be fine for at least 5000 miles. Which is why I use it for racing. For a street driven car you would want to use Eneos' 5w40
In the track car, the engine temp however did run 10 degrees cooler overall taking the average temp from several events before the switch to Eneos and then after the switch. The Supra also maintained 5psi of oil press. higher when it was
HOT!
So whether you need the 0w50 or 5w50 for racing, or 5w40 for your street car I have both available. The 50weights go for $9-$10 a quart where the 40weight is $7.