Low Noack plus Low HTHS??

[burla]

How can an oil brand have low noack and low hths w/o that being a feature of the base oil? Since both are high heat tests would you either expect good numbers in both, or bad numbers in both, not split? Unless you achieve a low NOACK with some type of additive other then base oil? Good numbers as in metal protection film strength not good as in fuel mileage considerations.

 

[bullwinkle]

NOACK seems to be a function of base oil quality-I have some of the PYB 5W20 from a couple years ago that was made with excess GTL base, giving it a NOACK of only 6.5%, but like most 5W20s, the HTHS is only around 2.9%.
https://www.pennzoil.com/en_us/prod...d07892b/Pennzoil-SAE-5W-20-Motor-Oil.pdf
Doesn't necessarily mean it's a bad oil, with it's healthy amount of Boron (119 PPM) and Molybdenum (272 PPM)-I wouldn't use it in a diesel, but it's good stuff for cleaning up a newer Ford modular engine that was designed to use 5W20.

 

[OVERKILL]

We are talking very different temperatures and tests here. One is a measure of viscosity under elevated (150C) temperatures, which are not unusual for an engine to reach, and under high shear, to primarily gauge the effect on viscosity that the shearing action has, which reduces it.

The other is a volatility test run at significantly higher temperature (250C) which heats a stationary sample of oil with air flowing across it, which burns off the lighter components.

 

[burla]

I would be misunderstood if you thinking in terms of a bad oil or not. Oils seam to be built for fuel mileage as a goal.

 

[ZeeOSix]

Originally Posted by burla
I would be misunderstood if you thinking in terms of a bad oil or not. Oils seam to be built for fuel mileage as a goal.


Only the thin stuff is "built for fuel mileage as a goal". Typically, the thinner the viscosity, the lower the HTHS.