Join Date: Jun 2006
The first number in the viscosity scale is denoted with a "w". This stands for "winter" not weight, meaning the oils viscosity at 32 deg. If you live in a cold climate, you should pay attention to this number closely. If you live in a warm climate, then the difference between 0 and 5 is undecernable. The second number is the oils viscosity at operating temperature, always go with the proper weight here.
The only proper way to tell which oil is best is through the American Petroleum Institute (API) tests called : TFOUT (D-4742) test which measures how long(when oxidized) the oil will resist breakdown, High Temp/High Shear (D-4583) test which measures under severe conditions the oils viscosity stability, NOACK Volitility (D-5800) test which measures how much evaporation loss takes place, A Total Base Number (D-2896) test which measures how well the oil controls acids, and (my personal favorite) a Four Ball Wear Test (D-4172) test which measures protection provided under pressure and sliding motion. There are a couple more tests but they relate to cold conditions and I am assuming the majority of us wont go 4 wheeling in an snow/ice storm.
I dont think the info comparing all oils is compiled in any one place, so one has to go to each manufacturer and do it yourself.
Here is some of my research:
1) Royal Purple has the highest TFOUT test numbers with ~1200 min.
BG Products is second with ~1000 min.
AMSOIL at about 500 min (they terminated their test at 500 min for some odd reason)
Mobil 1 at ~467 min
2) High Tem/High Shear winner was BG Products "High-Low 40"
3) Noack Volitility Test champ was BG Products "High-Low 40"
4) Total Base Number Winner Was Bg Products "High-Low 40"
Royal Purple (I couldnt find results from this test)
5) 4 Ball Wear Test champ was BG's "High-Low 40"
** I can't seem to find Redlines info from these tests.
Now mind you, all of these manufacturers can change their formulation at any time and re-test.
So, just stick to the top 4 that you measure this way.
I know, probably TMI for you. Automotive chemicals and lubricants are my business so I could go on for days.....but I'll spare you.
06 Lotus Sport Elise #15/50
Last edited by DARBY#33; 09-09-2006 at 06:40 PM.