Increase in wear following oil change...

[Shipo]

A year or so ago I stumbled across a thread here at BITOG that showed some interesting data that suggested that engine wear would initially go up following an oil change, only to drop back to normal levels a thousand or two miles later.

Do any of y'all remember what the name of that thread was, or better yet have a link to it? If you do and could post it, I'd be obliged.

 

[GMFan]

http://neptune.spacebears.com/cars/stories/mobil1.html

Quote:

While the wear metals all accumulated steadily over the course of the test, the highest concentrations of accumulation per mile occurred in the first 3,000 miles of the test! From the 3,000-mile mark all the way to 18,000 miles, only lead showed an increase in per-mile wear beyond 3,000 miles. Yet even with an increased wear rate, lead wore the least in terms of absolute wear. For iron and copper, the longer the oil remained in service, the lower the wear rate got.

In case it isn't obvious yet, this means that the most wear occurs in the first 3,000 miles.

 

[GROUCHO MARX]

I think this may be it

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Main=12981&Number=179215#Post179215

Time for bed

 

[Shipo]

GMFan and GROUCHO MARX, thanks much. You two rule.

 

[AEHaas]

All of the studies I have seen have been misinterpreted and are flawed. Most are bench studies. No study used new identical engines and put new oil in one and used oil in another from the start. I do not believe that used oil is better than new for wear protection at all.

I would think that Mobil would take some of their oils, heat them up and then run them through some kind of mechanical device. Then they could sell it as a processed, "improved" oil with even less wear.

aehaas

 

[Shipo]

Originally Posted By: AEHaas
All of the studies I have seen have been misinterpreted and are flawed. Most are bench studies. No study used new identical engines and put new oil in one and used oil in another from the start. I do not believe that used oil is better than new for wear protection at all.

I would think that Mobil would take some of their oils, heat them up and then run them through some kind of mechanical device. Then they could sell it as a processed, "improved" oil with even less wear.

aehaas


I agree that the jury is still out on this issue, that said, I saw a technical paper over in the SAE technical archive a year ago or so that also suggests that there is something to this argument. If I find the link I'll post the abstract.

With the above in mind, given that I am a firm believer in extended oil change intervals with synthetic oil (and have stellar UOAs to back them up), the issue of high wear following an oil change really doesn't mean much to me in a real world sense. Said another way, I'm researching this issue more for the knowledge than for any practice altering information.

 

[JAG]

Measuring wear with UOAs is not the way to do it, however in this case UOA wear data does match what the much better way of measuring wear of using radiotracers has shown: that wear rates are higher in the early stages of an oil fill than the later steady-state wear. SWRI has used radiotracers to measure wear rates for over 20 years. Below is a paragraph from their results linked here: http://www.swri.org/3pubs/IRD1999/03912699.htm

I think they did a later study dedicated to this topic but I couldn't find it. I'll keep looking.

"Testing with partially stressed oil, which contained some wear debris, produced less wear than testing with clean oil. This finding was unexpected and initially confusing (further inquiry suggested that the result was not so surprising, as many oil chemistries require time and temperature to enhance their effectiveness). Although based on limited data, the finding could be significant, and verification should be pursued. If the finding is verified, the mechanisms should be determined, and ramifications with respect to oil change intervals, filter involvement, and additive packages should be considered. A similar finding for diesel engines could have even greater significance, since the topics of extended oil drain and, in some cases heavy exhaust gas recirculation are of major interest. Although the conditioning run altered the oil, it did not stress or render it unusable (as noted, there is indication that it was tribologically improved). As such, the impact of testing with significantly stressed oil was not measured and remains a future objective."