I'll post this and then quit beating the dead horse. 
Some of what I'm writing is off the subject and I apologise for it's length. Let me say right now this isn't an endorsement of one product over another as there are many GOOD ones out there - I've seen the analysis on them, since after all we needed to know what the competition had!
When I worked for Frontier Lubricants, our primary focus of sales are directed towards Mining and Industrial applications, where the company had worked 30 years developing lubricants to address some specific issues. As such I saw far more analysis results for diesel engines than gasoline or natural gas fueled units, but the results were very similar. Of course the company employees took advantage of the free testing we were offered (thru an independent, certified lab), so our vehicles became rolling test platforms as well.
The primary questions about using an extended life motor oil were (1) Compatibility (2) Expense vs. Cost effectiveness (3)
How long between oil & filter changes (4) Engine wear.
(1) The newer CJ-4 (diesel) & SL (gas) oils are backwards compatible with older engines, and are required with modern emission controlled engines.
FYI - For those that don't already know this, modern diesel engines have Catalytic converters, exhaust particulate traps, and EGR valves. The hydrocracking process used to refine low sulphur diesel fuel has compounded the problems of creating additive packages that can balance anti-wear properties, blow-by resultant acid neutralisation, detergent, and end gas emissions.
(2) An oil that costs twice as much but has double the change interval is more cost effective, once down time, labor burdon, and filter expense is factored in.
(3) Change intervals are FAR more affected by the dirt contamination (as introduced thru the intake air filter) than the oil's ability to neutralise the acids created in the combustion process.
A high detergent oil will keep these particles in suspension, where they travel to the filter for trapment. A very fine micron full flow filter will have a short life in these operating conditions, and will bypass once the restriction becomes severe. It is normal to see secondary oil filters in industrial applications and centrifuge separators in marine use.
Due to the high detergent package in Frontier's oil, It was normal to see existing deposits break down and they recommended changing the oil and filter at the normal interval for the first change. Being the anal-retentive guy I am, I change my filter every 5,000 miles on my pickup.
Based on a regular analysis program, many fleets went 40,000 miles between changes. It was normal to see almost 20,000 in automotive applications.
(4) Engine wear with high zinc content motor oils was very predictable if they didn't become contaminated by dirt (silicone) or antifreeze leaks (it attacks the bearings). It was normal to see large engines go over 30,000 hours between rebuilds.
I chose one site at random that can give a good overview of oil systems and how stuff works.
http://www.synlube.com/oilfilters.htmBack in the day, I saw Golden Spectro perform wonders in my pals worn out Suzuki. It was still a smoker but shifted smoothly...
Lastly, use a high quality lubricant on your firearms. I witnessed an incident where in sub zero weather the firing pin became gummed up in a bolt action rifle, the spring tension could not overcome the resistace of the jelled lube to strike the primer with enough force to fire!
