Is that an article that you have just posted, or has it been on BITOG for a while? Regardless, thanks for the educational read!

Great article.

Wrote the bulk of it this month on vacation; been in editing and formatting for about a week.

Very nice.

Very good article, what oil do you like based on all of the UOAs you have seen ? Are you a thick or thin oil believer ?

Excellent article

Thank you for the great article, Dave!

Thanks Dave!

Since leaving Oil in longer is better for wear numbers would it make sense to change the Oil filter in between Oil changes ?

That was a great article. Very enlightening. Wear rates going down as the oil gets more miles was very informative. Thank you for the enlightening information.

Really informative.
We here tend to get all excited about small differences in wear metals per thousand miles, but you have put it in perspective.
Maybe the only real use of UOAs is to find gross anomalies, like coolant leaking into the engine oil, or TBN and TAN as well as shear to determine oil life.

Why? Filter efficiency increases with age/miles as well.

Only if you have a seriously sludged up engine that you should change filter more frequently, but then you should not be running extended OCIs either.

I agree. I'm thinking about leaving cartridge oil filter in the E430 for 2 OCI's of 10-12k miles each OCI. I will inspect the oil filter carefully on the next oil change and re-use it if the filter is in good shape and I don't see any debris. The capacity of the fleece filter is more than 10 grams, it is not possible for the engine to generate more than 2-3 grams in 10k miles.

The only way to know for sure it to get some PCs done (particle count analysis).

However, I would contend this; the OEM typically is as conservative with the FCI as they are the OCI.

There are a few notable exceptions. One such example is my (new to me) 2000 Galant with 2.4L engine. The "normal" OCI is 7.5k miles and the FCI is every other oil change, hence every 15k miles. That is with any filter that meets their OEM specs. And there are a whole host of filters from Purolator, Wix, Fram, etc that meet/exceed those specs, right on Wally's shelf. I am not saying all FCIs can be extended that far, but I am saying that as long as your UOA is showing good lube and engine health, the FCI should be able to at least go as long as the OCI. Only if your soot/involubles/oxidation were the drastically escalate in the UOA, would it indicate a need for FCI.

For my vehicles in warranty, (which I'm now down to only one), I am following the OEM criteria for O/FCIs. But for my other stuff, I'm beginning to push even the "normal" OCIs out and using the same filter for that duration.

I am going to put my money where my mouth is, too. I have an upcoming trip out west; we'll be taking my 1995 Villager that has 225k miles on it, and an estimated 6k on the oil by the time we leave. I expect it will have near 10k miles on the lube when we return. I look forward to seeing the UOA when I get back. Am I nervous? You bet I am; I'm always nervous a bit when I try something new. But I have faith in my data streams and SAE studies I've read. This is solid science; just because it's hard to believe, do not make it untrue.