A UOA isn’t a “toy” to see who can get the lowest wear. A UOA is a tool to see how far you can extend any sump load to a reasonably safe level of operation.
In a well designed and applied maintenance program, you set acceptable limits for wear data and other characteristics such as contaminant loads, and then operate the lube up to, but not past, those limits. You may have 20 or 30 different traits you’re following, and any one (or combination thereof) could push the lube past an acceptable limit and warrant an OCI. It might be soot, it might be vis, it might be wear metals, FP, etc.
But the key is to set safe operational acceptable limits, and then operate as long as practically possible while staying under those limits. The mistake that nearly all people make when reading (or should I say “misreading”) a UOA is that they think the lowest wear numbers means it’s a winner. The goal is NOT to get the lowest wear number; the goal is to extend the OCI out as far as safely possible and stay within acceptable wear parameters as well as total magnitude limits. You may have a great Fe wear rate, but if you’ve run the lube for 100k miles and the Fe is at 477ppm, you’ve over-extended the lube. Wear rates are only part of the story; total load limits also come into play. To truly manage the maintenance program, one must track both wear rates and overall wear, along with the contaminants and other traits. Depending upon each situation, one sets levels of condemnation for each trait; xx ppm of Fe, yy ppm of Cu, zz.z of Vis, xx% of soot, etc, etc. Until you reach one of those, it’s safe to continue to operate the lube. TOTAL WEAR speaks to a condemation level; WEAR RATES speak to operational fiscal choices. They are related, but they are NOT the same.
If lowest wear numbers were always the goal, one can easily artificially augment the wear with things like shorter OCIs and top-offs, to bounce the numbers around as desired. Wear rates are NOT constant; they are reasonably predictable in long term studies, but they are NOT linear by any means. They have parabolic curve responses shortly after an OCI, then they flatten out, and then escalate once again after the base stock and additive package are compromised.
To that goal, there are several different approaches. One is synthetics (often teamed with bypass filtration) and the other is shorter OCIs with less expensive oil and filters. Either method can keep the attributes within a safe operating zone. So the real issue becomes one of cost; which method is “cheaper”?
You mentioned HTHS as if it were the golden egg. There is a similar parable that will not die in the HDEO arena. People often get very squeamish around a loss of viscosity, especially in a PSD, but the actual evidence of wear shows there is no real correlation between a loss of grade (from a 40 to a 30) and an escalation of wear. The myth dies hard, but the facts are there for those that look at them. I would suggest that the same can be said for HTHS ratings. Yes, they are important. But the issue is one of use factor. Oil with a lower HTHS may not last quite as long in the sump, but that does not mean it degrades and goes to Hades as soon as it hits the pan. There is some portion of time where it performs admirably, but just not as long as an oil with a higher rating.
ANY oil can be used for too long, or not long enough. The people that really understand the true use of UOAs realize that this isn’t as a toy, but rather a tool to predict a sensible end to the useable lifecycle of any lubricant when viewing the entire set of data. You see, the correct approach is to develop safe condemnation levels for the lube, and then push out the OCI as far as possible; that will gain the greatest return for the investment regardless of the type and brand of oil. Unfortunately, most people want to limit the OCI, and then play a game to see who can get the lowest numerical number for some particular trait; that is NOT how a UOA should be used.
To bring this full circle, you have a great UOA, but what are the condemnation levels you’ve set for this vehicle? You mention (or at least infer) that you have a “fleet” to maintain. Do you have a fleet of 2.5L Subies, or is this just a one-off experiment in your garage? And what are you going to do to achieve the ROI? You said you’ve tried cheaper group III oils, but made no mention of what criteria they failed to be judged inferior. What “average” distance were you getting out of them as compared to your condemnation limits for your fleet? You said you had 750k miles of fleet data; please give specific details as to the type of vehicles, type of use, lubes used, etc, etc.
You asked if this would be a “fair fight” in regard to motors that “have been destroyed due to lubrication failures from heat”; I would ask just how many Subie 2.5L engines you’ve had to rebuild in this “fleet” of yours that were destroyed by these other inferior oils due to HTHS failure? Am I supposed to believe that you are in such a unique situation that ONLY RedLine products will survive, and all others fail, due to heat? Are you suggesting that Amsoil would fail? And what of RP or M1? If you’re having motors "destroyed" related to heat, that tells me you were not properly maintaining the vehicles in the first place, because you were not tracking the “other” lubes close enough to catch failures before they occurred. Like I said, ANY oil can be over-utilized regardless of base stock and additive package; sounds to me like you didn’t track the “heat failed” engines close enough, and then blamed the oil for a poor maintenance management program. You said you've seen a shift in the "mechanical failure statistics"; what is the shift? How many "mechanical failures" are you seeing pre and post RL? How many engines have true mechanical failure due to HTHS degredation and not component failure? Are you stating that you're seeing multiple engines actually fail mechanically due to the oil selection? How many? What parts? How many miles? What fluids and conditions? Frankly, that's a pretty heady comment to make and I'd like to understand the basis for the statment.
You are correct in that I made assumptions, but then if you’re leaving out important data, how would we know otherwise? If you’ve run other oils, and done UOAs, then why not post them along with this UOA so that we can compare/contrast the performance differences? Why not tell us the condemnation levels you set for this 2.5L Subie? Show us that RL is the ONLY lube that can survive this heat monster.
You have shown a great UOA, but you have not shown a great maintenance program. Anyone can manipulate the conditions of a UOA. Can you manage this RL and Subie to get your value from the program choices?
