Originally Posted By: ram_man
I posted a few days ago asking to see Dino engine pics. Saw a few and appreciate all those that contributed. However got me thinking if synthetic is really better not just for longer drains but better in general the wear would be less correct? Is there any kind of proof that says on a regular basis synthetic oils out perform Dino oils in this area?
IMO you have to draw a fine line between oil "performance", "wear", and the causes of wear. We know from simple physical tests that synthetics outperform in terms of flow, stability, viscosity retention, etc. With some more complex tests, we can see that they outperform in terms of oxidation, volatility, etc. And that's the case regardless of where the synthesized basestock is derived from, wither the basestock was a wax or was ethylene (also derived from crude).
The real play is in how these manifest themselves in performance. I would recommend you go back to stuy the basis of hydrodynamic lubrication - in other words, for finely finished surfaces with an appropriate film of lubricant (viscosity selection and its retention and behavior under shear and temperature do come into play here), there is no surface to surface contact, and as such, there is no practical wear.
So the benefits come to play in the following:
1) Better flow performance in the cold and from engine start - how fast you can create the hydrodynamic wedge means how short the time where surface lubrication occurs. For many applications, a non-syn can practically pump up at the same time as a syn. But in some circumstances, the syn will flow faster and get to the lowest wear regime soonest.
2) Better oxidation resistance - how fast the lubes degrade and change flow/shear/wear performance in both the hydrodnamic and other regimes. But to add to that, how fast/how much deposits, coatings, and viscosity changes occur.
3) Better viscosity performance - relates in a way to oxidative performance (in the case of oxidative thickening), but also in terms of how well viscosity is retained under high temperature, high shear conditions, where one may fal out of the hydrodynamic regime and into a higher-wear surface lubrication regims
4) Longevity of the lubricant - related to many of the parameters up above, but important in and of itself, since the performance of the lube in every way changes.
It should be noted that for some base stocks, some additive solubility parameters may be worse than other base stocks. Thus there may be other issues with the approach to additization, the ability to disperse and support contaminants, TBN retention characteristics, etc. Ive said it before and Ill continue to say that the add pack makes at least half of the difference in terms of a finished lube performance. Thats a big reason why for all but the most extreme (generally cold) conditions where pumpability is requirement #1 (and since most of us dont live in Alaska or Fargo or on the Hudson Bay, its not that substantial a concern necessarily) conditions, the use of PAO versus a good group III lube or anything similar is such a moot point and only makes the tiniest of a fraction of difference (and precisely why lots of vehicles have racked up tons of miles on older dino lubes and whatnot). The whole basestock wife's tale "value proposition" is silly, and its all about how good the finished lube is.
And given ever more stringent specs in terms of API and other versions, it is driving ever better feedstocks (syn or not), add packs, and other components. Thats not to say that PU wont outperfom PYB for the same API SN certification, or that Edge or M1 wont outperform GTX or clean for the same specs. They will. But the practical reality of if it will be seen is highly engine and use dependent, and is also contingent with how many/much/often the more difficult conditions I mentioned above are to be encountered.