Originally Posted By: theaveng
Originally Posted By: 2010_FX4
synthetics are not always needed, they can be a waste of money, and they are not always "better".
The natural oil is leaving behind VI modifiers and varnish which can't be sen in oil analysis. If this was my car, I would at least upgrade to the Mobil Super Synthetic.
So your recommendation for his running at or near OEM OCIs is synthetic? Did you happen to notice he's already run MANY OCIs with that practice?
Sludge and varnish contributing components will show up in a Blackstone UOA, listed as insolubles. "Insolubles" includes not only oxidation and sludge, but also soot, as well as anything else that is not soluble (hence the term). It is a reasonable predictor of the tendency of the lube to want to form sludge. It is not an assurance, but it is a good predictor.
Light varnish is pretty much harmless in an ICE, and occurs as a discoloration of the metal surfaces. Varnish is much more of a concern in a turbine engine; that's not applicable here.
Sludge is certainly something to be avoided, but it's not as common as folks think, and is often moreso a function of poor engine design and not oil choice. His 5.4L engine (a Triton motor) is based on the mod-motor Ford engine family; they are not known to be sludgers, and are some of the better wearing engines produced in the last two decades. I have more than 600 UOAs for mod-motors (4.6, 5.4, 6.8), along with the statistical analysis to back up that statement.
Some amount of oxidation is actually beneficial; proven to be necesary to form the tribochemical barrier anti-wear layer, as seen in multiple SAE studies. Check out my UOA article on the lead website page for details.
Additionally, using synthetics is not an assurance of sludge being avoided; to the contrary, it might actually promote the very problem you are trying to avoid! Allow me to quote from a Noria article by Fitch:
"Additionally, we are seeing increasing use of low-solvency basestocks (hydrocracked and PAOs for instance) that could be amplifying problems. These basestocks, on one hand, are more thermally and oxidatively robust. On the other hand, they may be more prone to lay down and coagulate oil degradation products (oxides, salts, carbon fines, etc.), leading to sludge and varnish."
WHAT?????? A man (Fitch) with years of UOA analysis experience states that while the synthetic base stocks are more robust, the end result of the entire lube package may actually be counter productive? That is probably painful for a syn-loving-BITOGer to hear. What he is pointing out is that while synthetics to tend to resist the formation of oxidation/sludge, they also are more prone to deposit them once they do form! In short, synthetics will likely resist the development of sludge "better", but cannot hold those components in suspension as well and may subsequently drop them onto the part surfaces.
Nearly EVERYTHING in life has a trade off. Synthetics are great products when used in conditions that would differentiate their performance above alternatives. And as much as it might shock folks, I actually do use synthetics in some of my equipment. But they are not a one-size-fits-all answer for every application, and they do have negatives to off-set their positives. Even the term "synthetic" itself is too broad, because the different bases of synthetics do have different pros/cons.
If you believe that 2010_FX4 is at risk for sludge formation by using a quality conventional lube at/near OEM OCIs in his mod-motor, then I would ask for your statistical proof that the risk exists, and show documented proof of the results of your claim.