PAO doesn't have high film strength? News to me. Oxidative stability and long drain capability are also strong points.
M1 Extended Performance - Group IV?
- Thread starter WillB
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Yes that's true. For about $26 u.s. we can get good stuff like PUP, Castrol EP, Mobil1 EP when on sale a few times per year at Canadian Tire. Unfortunately they don't carry Valvoline.
Film strength is not a significant property of motor oils. There is no ASTM test for engine oils so what is a “good” value and what is a better one?
How is it measured?
It's usually an AN signature I think. The ESP line and 0w40 use POE.
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Correct me if I'm wrong, but isn't pao content basically for extreme cold performance?
Yeah PAO is basically used like an additive these days in varying %'s depending on the performance demands required. PAOs generally have better low temp ability and oxidation stability.
If there isn't a method to measure film strength then I am mistaken or I just never read what I thought I did. I don't understand why it wouldn't be a significant property if it could be measured though. So exactly what are we referring to when film strength is mentioned, hths or maybe aw package?
Cheapest and -40 do not play well together. I plan on keeping this truck a long time, cheapest won't be getting bought. I'd rather pay more for a full synthetic for superior cold starts.
Next change will be Rotella gas truck 5w30, the change after that will be Amsoil.
Best approximation is probably to say it's called HTHS viscosity. HTHS viscosity
directly translates to "film strength". Viscosity at elevated temperature and under
shear stress is what matters. So I'd say yes, it does matter. As a consequence there's
no need to measure film strength directly since we have HTHS. I guess that pretty
much explains why there's no ASTM test existing.
.
At negative 40 you should be using 0W30.
....or 0W-20 with a pourpoint of -66°C. Only issue, it won't stay at -40°C/F the entire winter.
Polarity also plays into film strength. The more an oil is attracted to metal surfaces, the more force is needed to break the film.
I see higher flash point with Mobil 1 EP 0w20 than most oils, too. So doesn't that indicate PAO holds up better to high temps as well as having a lower pour point?
Good point, Tom. Unfortunately oil formulators have to balance PCMO formulations,
which pratically limits polarity. E.g. using "pure" ester base oils certainly wouldn't meet
seal compatibilty targets.
True for pure ester based PCMO, but some esters can be used at rather high dosages if seal balanced with some PAO. These tend to be lower polarity, high lubricity esters using long chain vegetable sourced fatty acids. Still as you say the PCMO formulator is restricted when it comes to polarity. For aviation and industrial applications ester base oils can be used at 100%, and the seals are selected for compatibility with the ester rather than the other way around.
*You can thank Castrol for going to court to contest what can be labeled as a synthetic oil ... Of the readily available brands of oil from off the shelf at WM - the M1 EP oils is the truest synthetic oil you can buy due to % of PAO content (for some people that is important) .
Or didn't go to court.
It just won't die.
Funny, I haven't seen NAD (of the BBB) sending anyone off to Jail ...
I find you guilty of Group III basestock blending!
20 years to life ! Take the defendant, Mr. Fidel Castrol, away !
And had it gone to court Mobil knew they would lose since they (and Castrol) had been selling Group III based synthetics in most of the rest of the world for years. The US was actually a latecomer to the change.
I had not known that, but I believe it. They were likely keeping and eye on what RDS was doing with slack wax and making a well received lubricant out of byproduct, ss well as other technologies. How could any significant players not do this.
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