Originally Posted By: Tempest
You know this how?
Tempest, I've talked about this so many times here I can't believe you've missed it, or maybe you're just picking this particular time to jump in. Anyway fair enough:
Conventional vs. synthetic wear. Like a lot of people I was a confirmed synthetic user before finding this site. However, it didn't take me all that long to figure out that going by UOAs, synthetics didn't seem to offer any advantages over conventionals. Instead, the more I looked at UOAs, the more I had to admit that often it seemed that the best, those with really exceptionally low wear, often occurred with conventional oils. Data points to consider:
- The makers of synthetic oils do not generally claim any wear benefits for their products. Surely if wear benefits existed, they would claim them. Could it be that public perception has erroneously equated synthetics with reduced wear due to broad public awareness of synthetics' other benefits? I think so.
- Most of the exceptionally high mileage engines I have heard of, such as the recent 1,000,000 mile Chevy, seem to have been run on conventionals. No doubt the population of conventional-fed engines is higher, especially among older vehicles, but this does corroborate my opinion and consequently I offer it as something to consider.
- Oils get their ability to attach to metals from polarity. As oils are more highly refined they become "saturated," making them both more stable and less polar. PAOs are fully saturated and non-polar, and need to be mixed with lower-group or Grp V oils to perform properly. Since wear peformance equates largely with boundary lubrication, and boundary lubrication depends largely on film strength, it seems reasonable to consider that there might be a trade-off in wear performance as one goes up the scale from basic conventionals to PAOs, and that it might be difficult to completely correct for that trade-off via improved anti-wear and/or the blending of some polar components into the oil.
- Very frequently, in the UOA section, an engine that has a long history of UOAs, in which it has been switched between conventionals and synthetics, will actually show significantly better wear results (per mile) with the conventional. Pointing this out always results in the obvious counterpoint that it is only one data point and far from scientifically significant in any given case - but it seems to happen so often that I do personally believe it is, overall, indicative of a pattern. Try to find examples of the opposite - reduced wear when switching to a synthetic - and you will find it difficult.
It is clear to me that synthetics can be blended to offer excellent performance, and the difference if there is one is probably inconsequential over the ordinary lifespan of an engine. However, I do believe, personally, that conventionals, when changed at appropriate intervals, have at least a slight edge in wear performance over synthetics. I've said this many times before. I do not have sufficient confidence in this to state it as a matter of fact, and so I always state it as a matter of opinion.
As to Redline's metals being the results of chemical action rather than wear, this too has been said many times here, by people other than myself and people much more knowledgeable than myself, and I can not claim it as my own insight. I believe it, and I repeat it as a generally accepted matter of understanding. I can support it, however, at least in general terms:
Consider again the polarity issue. If you see a continuum between polar conventionals and non-polar PAOs, POEs exist outside of that continuum, having both the stability of PAOs (different, better in some ways, worse in others, but excellent overall) and a high degree of polarity. Much more polarity than conventionals. They do not need to be mixed with anything else for performance as a lubricant, although they usually are for other reasons, and Redline uses some PAOs, nobody knows how much, in their oils.
Yes, of course any PAO that is blended with POEs will gain the advantages of the POEs, to some degree, and it also makes sense that it would gain some of the "cleaning" characteristics of an oil like Redline, and that consequently some of the observed wear from certain synthetics would be attributable to this the same way it is with Redline. However, it is hard enough (impossible?) to figure out to what degree this is the case with Redline, which we can be confident is a majority-POE oil - it is that much harder still with an oil where we do not have any idea of the POE content, or even if it has any POE at all, as it might instead have been blended using lower-group oils for its polar content. If the Redline issue is sort of like a single equation with two variables, where we have to make educated guesses about one variable in order to determine the result for another, doing so for an oil where we have no idea of the mix is rather like having yet another, third, variable to guess at. Is some of the "wear" from cleaning, or is it due to an oil having been blended more for stability and long drains than for the best possible wear performance?
One valuable hint, it seems to me, is to look at an oil's measured film strength as shown by HTHS results. HTHS is often said in technical articles and the like to be the best overall correlant to wear protection in an oil, which makes sense as it is a measure of the oil's ability to cling to the metal surfaces under duress. If one accepts that this clinging ability is likely to work both ways, both attaching the oil to the metal and also giving the oil the ability to pull metal away from engine surfaces, then one might conclude that those oils with the highest HTHS will also likely show the largest degrees of "cleaning" in an engine - that is, of inflated metals numbers in UOA that do not represent actual wear. Redline, in all grades, has just about the highest HTHS values of any oil available, often by large margins.
Some other premium synthetics, such as some of Amsoil's products, also have relatively high HTHS, and it would be reasonable I think to assume that they are probably blended with significant proportions of high-quality polar base components such as POEs, and that their UOA results are similarly artificially inflated, though probably by a lesser degree than Redlines'.
My tendency is to gravitate either to the obvious choice of low-cost, excellent-performing conventionals, which so often show outstanding UOA results, or to Redline, with its very high-POE, high-HTHS qualities, as the two best possibilities when looking for the lowest-wearing oil.
Note, by the way, that I have never said that Redline is the best oil or that it produces the lowest wear, only that as far as I can tell it might be the best oil. Again, I don't have the confidence in that conclusion to state it as a fact, or even as a solid matter of opinion. At least I am putting my money where my mouth is by using it, by experimenting, by doing UOAs, and so on.
