Well Mark,
Sorry but soap puts impurities in suspension as well, why do you think they call the additives in oil detergent??? remember oil's job is to also keep your engine clean (soap aka detergent) and cool, dirty oil does a substantially worse job at both of these even if it "lubricates". And if I'm using true synthetic oil then I'm not using any Dino oil so no gain there. So is your filter plugged and bypassing @ 12,000 miles? I bet you don't know. I don't know of many filters that will last 12,000 miles so it's probably bypassing? Most guys I know who run extended oil changes have very complex aftermarket filter setup's for that very reason. Spend your money on a lab if you like. but do a test. Send 2 samples from the same oil change to the same lab and see if you get the same results. A friend and myself did that very thing on his diesel pickup, one test said "normal" the other said "extreme limits" on some metals. A very well known lab. I put good oil in every 5k you go ahead and put your faith in a lab and a oil filter that is beyond capacity and we will see who's runs longer. And I stand corrected less than 1/2 cent per mile for a 5k oil change.
Of course, but soap and water is meant to washed away, and is not lubrcating your hands. Oil is meant to keep in circulation.. And yes, I know my filter is working just fine at 12000 miles. In fact, none of my engines have ever "dirtied up" any filter, even under the worst of conditions.
The lab returns good results and like anything tolerances vary. It is the trends you are looking for, not finite numbers. Since I have always praticed extended OCIs, and have never worn an engine out over 35+ years, and had well over 400000 miles on some... Well, I do not need to listen too closely to your advice.
Incidentally, I am a Mechanical Engineer with extensive experience in oil and mechanical engines and compressors. Today's Mobil 1 oils are better then they ever have been and really can go much longer than 12000 miles in a modern, well kept engine.... even with the use of a FRAM filter.