Mineral oil I think breaks down also. Synlube doesn't break down and produce sludge because it doesn't have the sulfur compounds in it like convential oils and it also relies on the solids Moly and PTFE to lubricate and the liquid part to carry the solids through the engine. It also seals the cylinder to ring area to reduce blowby and has graphite to absorb moisture when the lube and engine is cool and then releases the moisture from the graphite when the engine gets hot enough and vents the steam back through the PCV valve. The better filter they provide has does a much better job of filtering the oil along with Neo Magnets to remove trace metal particles.
Check out the postings by budman on his 50k run with Synlube.. He went from overboard advocate to "what was I thinking"....
The entire motor oil industry is up to thier elbows in hype...at SynLube, they appear to be up to thier necks.
Sorry JanGeo, but from where I'm standing trying SynLube is akin to joining a cult...you can't really join without becoming a believer.
__________________ 1993 Volvo 240 Wagon - 323k miles (awaiting recommissioning) 1999 Audi A6 Avant Quattro - 149k miles(the NEW daily driver)
One thing to consider is the testing done by Lou. Mostly at a steady speed 50 mph,with a fully warmed up vehicle.
I have no doubt you can get the same results with the same kind of testing, however most of us have to start cold, and there is no question that thinner oils will give you better FE during warmup, esp. in winter.
But I think this is a individual thing, your results will vary depending on the condition of your engine and the number of cold starts per tank.
around here our winters are usualyl around 15*F(avg) and it oh so nicely works out that late october/nov that i need to have an oil change so i usually switch over to 5w-30 in my truck and in the late spring to 10w30. my truck uses NO oil between changes so why mess with that works? it was designed to run on dino oil so its gonna be ran on dino oil...