Wayne, you asked for some sort of "proof" for my statement as to dino oil being capable of extended use - out to about 32,000 miles. Documentation for those specific articles are not in my database, going from memory on info read over the past several years on the issue - I *have* posted the specific material on one or another board in the past, and will try to locate one for posting here.
MEANWHILE, I *DID* do an Internet search on "extended oil drains", and came up with TONS of related info, covering both synthetics and dino-based oils - random samplings from a half-dozen or so sources are submitted below - and ALL of those are based upon dino-based lubes.
2 things will become immediately evident - most lube testing out in the "real world" is done on FLEETS of vehicles due to their tendency to pile up lots of miles in a short period of time, and also more consistent operating conditions with fewer anomolies to artificially slew results.
AND, most extended drain test scenarios are based upon, or include bypass oil filtration, with the significantly improved reduction in contaminant volume and particle size they provide.
Here's a few exerpts on extended drain, as presented by various lube industry experts:
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There is some evidence that synthetic oils can help extend oil drain intervals, but you have to carefully balance the price premium against expected savings. You may need to look beyond extending your drains and consider other benefits of synthetics, such as superior cold-weather starting and improved fuel mileage.
"Synthetic base oil tends to be able to survive the impact of heat longer, therefore the additive system is not under as great a stress, and the overall package is more durable in some of the areas that tend to break oil down," Betner says.
However, he warns fleet managers that synthetics are not a magic bullet when it comes to oil drain intervals.
"Synthetic oil can be misunderstood or misused in light of the many factors affecting drain interval," he says. "Keep in mind that various types of contaminants can be the limiting factor, and synthetic oils cannot overcome the negative impact of some of these contaminants, such as dirt and coolant contamination. "
Noal says, "When we talk to fleets about the increased ability of this technology to extend oil drains we use the term `optimize' to emphasize the fact that extended oil drains should not be the main focus for fleets looking to extend service intervals.
Even though we have fleets that are getting 50,000 to 60,000 miles between oil changes, we want to encourage fleets to look at all systems on the vehicle. Other components on the truck may need lubrication at shorter intervals than the desired engine drain and may suffer if the truck only comes in for servicing at those extended marks. "
Some aftermarket filter advertising claims might make you think that all you need to extend your oil drain intervals is to buy their filter. ChevronTexaco's Gary Parsons advises fleets against relying heavily on just the filter.
"They shouldn't assume just by putting a higher quality filter on will allow them to extend their service intervals," he says. "When it comes to the life of the oil, the filtration isn't usually the condemning limit. It's more the ability of the oil to neutralize acid. "
As for filters removing soot, he notes that if the oil is doing its job and keeping the soot dispersed, the particles will be too small - typically . 2 microns - to be caught by most filters.
Numerous tests and studies have shown that solid contaminants in the 1-15
micron range are responsible for the majority of normal wear within an engine.
Ninety-eight percent of the solid contaminants generated within engines is
below 10 microns in size.
A factory full-flow filter is designed to remove large particles that could damage vital parts. The full-flow filter does little to reduce normal wear within the engine.
The vast majority of solid contaminants generated within the engine are below 10 microns in size. As shown below, the full-flow filter is only capable of controlling 15-micron-and up articles, allowing the smaller size contaminants to pass into the lube oil. Once introduced to the lubrication system, the oil has the job of suspending these tiny particles within the additive package.
However, abrasive contaminants in the oil tend to grind away at bearings, cams, and other engine parts, causing the normal wear. UF by-pass filters are capable of removing and controlling particles down to 1-micron size range. By using UF by-pass filtration, fleets can accomplish extended engine life.
ExxonMobil's Bolkhovsky recommends taking a step-by-step approach to extending oil drain intervals.
"Let's say you're going out to 40,000 miles as your targeted goal for oil drain extension and you're currently at 20,000 miles," he says. "You probably don't want to move from 20,000 to 40,000 in one step, taking a big risk with your equipment. You move to 30,000 miles and look at what the data is telling you, then your next step would probably be to 40,000. "
If your fleet is large enough, Bolkhovsky suggests taking a small subset of your equipment and testing the extended drains on them first. Test the vehicles that are run under the most severe conditions first. If they can handle the extended drain interval, then your less-stressed engines should have no problem.
You also want to check at oil drain intervals beyond where you want to end up to make sure you have a safety factor built in.
"If you want to go to 30,000, you might want to take it out to 35,000 or 38,000 and then back it off a little to make sure there's a safety factor there," says Spinner II's Weaver.
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SO, there you have several references to pretty high mileage use on dino-based lubes.
And for the record, *I* have never downplayed the additional benefits provided by synthetics over dino-based lubes - I only question their actual value vs greater expense for the AVERAGE truck owner as represented by this group - and I have steadily resisted the implication that only synthetics were worthy of consideration in extended mileage use.
Cuz THAT just ain't true!
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