Understanding oil specifications - Penn vs Castrol

[Mossyoakglock]

Can somebody help me understand the different oil specifications like pour point, viscosity at 40*C, TBN, Noack, etc? Just a quick guide like when is a higher number better and when is a lower number better?

I'm currently running Castrol Edge Synthetic and I am considering switching to Pennzoil Ultra (will run Platinum if I can't find Ultra) and want to see which one is better. Running 5w30 in a 2008 Chevrolet Silverado 5.3L.

People here can probably tell me before I can learn but which one is better on paper (all bias aside, looking for information based strictly on technical specs)?

 

[Kuato]

I'll give it a try but there are more educated folks that will be along....hopefully I won't get bashed too badly.

Pour Point: the lowest temp at which the oil will pour, pour being defined by the testing specifications. Lower is better, indicating cold weather protection. But since you're in Nashville, a 5w30 will do you fine year round.

Viscosity is measured in centistokes, abbreviated CsT or CST depending on who you are talking to. It is a comparative measurement of resistance to flow. At startup, your oil will be heavier so a lower number here is generally better as an oil that flows better will be reaching your moving parts more quickly.

TBN: Total Base Number. The quantity of additives in the oil. More is better as the oil can last longer and will hold up better under stress; but if you are doing shorter OCIs then a high TBN isn't necessarily required.

Noack: this is volatility, as in how much oil you will lose due to vaporization (insert more detailed description here) over time. Lower is better and indicates a more stable oil in that regard.


You will get lots of suggestions as to which oil to use, so be prepared to tell what your driving habits and mileage are to get the best answers. Both the oils you mentioned are top notch and IMO can generally go at least 7500 miles without worry.

 

[danthaman1980]

http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Generally, you want low numbers for NOACK, viscosity @ 40C, and viscosity @ -30C. You want high numbers for Viscosity Index and TBN.

On paper, Pennzoil Ultra has better viscosity and NOACK characteristics but Castrol Edge has better starting TBN. Both are excellent oils. I've used all 3 of the oils you mentioned (5w30) in my 5.3, and Ultra is my preference - but it is a very, very, very close race.

 

[Mossyoakglock]

Thanks, guys.

I change my oil based on the OLM which is anywhere from 5000 - 7500 miles. Tow/haul a few times a year but nothing major so it's normally city/hwy day to day. Usually run Purolator PureOne or WIX.

What about CCS V, CCS T and CST at 100*C? Higher or lower better?

 

[Quattro Pete]

CCS - the lower, the better, but you have to remember that CCS is measured at different temps depending on which grade it is (0w-, 5w-, 10w-).

http://www.pqiamerica.com/Testdescriptions/Coldcrank25.html


cSt @ 100C is what determines the second number in the oil grade (Xw-20, Xw-30, Xw-40, etc.). It's not a matter of higher or lower is better. It's a matter of what your particular application calls for.

http://www.pqiamerica.com/viscosity.htm


The general rule should be: use an oil that's as thin as possible, and only as thick as necessary.