Just stumbled across this. The link to a website with really creepy music was intentionally left out....enjoy.
I've found a website that discusses the low vicosity oil that we use these days. Obviously, the oil tempurature is rated for the Antarctica which is very suspicious. But for arguements sake, the engine tollerances have been tightened up these days. From an engineers perspective if you tighten up the tollerances by just a few more microns it will last much longer, like triple or quadruple or even ten times so long as you change the oil on time. However, no one wants to say that thier new engines get almost a million miles on them which they could and as you know 100K miles is normal "lifetime" for the dealer. I personally believe that 5w-20 oil is too low yet somehow was rated with less friction with the intention of wearing out your engine faster. This one website I found says that the gas mileage increases less than a tenth of a mile per gallon but wears out your engine much faster. SAE 5W-20 Remember "oil is like liquid ball bearings"? Oil fills the gap between moving metal parts. The more worn out and bigger gaps, the thicker oil vicosity is needed. But now we have new tighter tollerance engines and perhaps we could use a lower vicosity. However, 5w-30 is MORE protection than 5w-20 simply because it is a range. Your oil thins out when it's hot. After using thick vicosity for old cars I can tell that thicker oil also lasts longer than thin oil, seems the heat breaks it down to become thinner as time goes by. Ever since the year 2000, other than cars for sale, any new invention or new sales in America has most likely been a scam in someway and never saves people money despite all the huge claims and optimism seminars. Could it be that 5w-20 is a scam? I bet the "tests" were done with fresh oil and never do they want to reveal how long thinner oil lasts compared to thicker. I wouldn't doubt that 10w-30 is the best bet being longer lasting and enough protection. I bet after 1500 miles 5w-20 is suddenly like water wearing out your engine like stupid.