Just to add another note. Full flow filters (general spin-ons) are considered "emergency debris catchers" and generally only capture particles larger then 100 microns.
Recent post on the usefulness of standard oil filters
Some can catch particles as small as 20 microns, but the % caught is very small in comparison to the larger particles.
Its been shown that particles as small as 5 micron can cause bearing wear, and filters miss alot of these. Thus why "bypass" filters came into use. A filtration system which can filter down to 2 microns, but can only do so when the oil is in a bypass state.
Since you disregard the manufacturer recommendations in terms of oil selection...I wonder what type of filter your using. I hope its not a fram.
Thus the particles contained within a UOA ARE very important, and do indicate the overall wear of the engine, its breakin, possible leaks, possible fuel problems, and possible issues with the filtration system and/or engine.
Disregarding a UOA because the particles are too small to do harm is like disregarding your blood work because if the liver didn't filter it out, it can't be bad for you.
Information on UOA importantance and validity (both sides)
UOA's show that an early oil change can flush alot of the remants of breakin and factory castings out of the engine oil. Do you have to do it?No, of course not. Is it recommended? Yup. Considering motorcraft 5w-20 semi-synthetic (the stock oil) costs 1.40/qt, its not really a big expense to change it out early.
I'd imagine your primary counterpoint to UOA's not providing factual information is based on the recent evidence showing that overly thick oils (such as your 20w-60) can cause unnecessary wear to an engine designed to run on 20/30 wts. This is primarily due to startup viscosity's, and oil temps. The fact that the VVT system relys on oil flow to function properly doesn't help much either. Additionally should your engine ever enounter an issue and have a mazda teardown, it is part of the teardown that a UOA is done on the oil in the engine. If the viscosity of that oil is out of manfuacturer specifics, the engine warranty is null and void. This has happened on the bob's forum. The same thing can happen if you extend an OCI (oil change interval) past the manufacturer required limits. There is usually some leeway room (some 20 wt's thicker to 30 wts, and most 30 wts are 20 wt's) but a drastic difference will be extremely easy to spot. Don't count on the oil companies to help you either. Thats all a giant load of bs as one amsoil owner recently found out.
As always with any application, its important to look at the manufacturers recommendations and past history of the engine before making a selection on oil grades.
Are good sources for past history of the duratec platform, both in 2.5 and 3.0 variants. Considering some of their engines make peak power at 7600 rpm (with an 8k redline) and they're running 5w-30 mobil1 in 100F summer heat (racing), and have hundreds of thousands of miles on their engines without issues (as long as you don't let the oil level drop), that speaks more volumes then anything I can ever post here.
I suggest doing a Dyson analysis through blackstone-labs, and having terry dyson (a tribologist) look over your readings on the 20w-60. Terry used to do the UOA's for the tripoint racing teams in the SCCA World Challenge Series, and is more then competent at doing so for a commuter car.
He can also recommend an oil application based on your application, for maximum protection, maximum power, and maximum longevity.
Tripoint btw, was running a 40 wt oil in their car, and has dropped the weight down to an oil which would probably result in the engines instant destruction in your eyes. (5w-20 and 10w-30 redline) [280 bhp, 8500 redline mazda 6, no engine rebuilds allowed during the season]