I read all three links.....with the exception of Machinery Lubrication the other two links were individual companies trying to sell you THEIR product. Several comments and thoughts came to mind:
1. I moved here from Scotland, and from what I remember cars did seem to last longer over there, engines would not die but the bodies would rust out due to the salt and climate. Even over here I see more older small cars than I do see older large trucks so maybe it has something to do with engine size and what they are used for and what type of person drives those vehicles.
2. The article states that 5W20 is a preferred lube for large vehicles, SUV, trucks, etc......there are no large vehicles in countries or areas that can compare to North America so that might be a reason why it is not readily available.......there is not the same market.
3. The article states that Federal law says you will not invalidate your warranty, how does that apply in Canada? Anyone know?
4. If it ever got out that say Dodge were doing this deliberately to limit vehicle life to buy another one they would be toast, no one would ever buy another product from them. Not saying it is not being done but it seems a huge risk.
5. The warranties vary from US to Canada where in US the RAM warranty is 100,000 miles but only 60,000 in Canada.........I still don't understand that.
6. In addition, the Federally mandated Magnuson - Moss Act states that a manufacturer may not require a specific brand or type of aftermarket product unless it is provided free of charge. If your dealership continues to tell you that you must use 5W-20 motor oil and or/ a specific brand of 5W-20 motor oil, then ask them to put it in writing. Their position is inaccurate, and, in fact violates existing law.*
IMO this statement is to increase competition amongst oil companies and not allowing manufacturers to say you must use Castrol GTX for your warranty.
I think that if you were using 5W30 in a RAM 1500 and you have engine issues during the warranty that if Chrysler asked to see your service book and/or receipts that if they found out you were using a different weight that they would say you invalidated your warranty and that if you are using oil that is not recommended that their position would be that you are causing unnecessary wear and tear.
With all that being said, I only ever change it by what is the minimum for the warranty and to date I have never had an engine die in what I would expect to be prematurely. Right now I am using 5W20 Synthetic, back 10 years or so ago I always dropped in a bottle of SLICK 50 every 40,000 miles. There are lots and lots of vehicles out there that do not get regular oil changes and serviced and still run hundreds of thousands of miles on them.
IMO it is just as much how you drive it and how hard you are being on it that will cause damage as much as ignoring or putting in the wrong oil.
As for the 1500 and 2500 differences in oil weight I always thought it was because of the MDS.
I do always try to look at arguments from both sides, but I can't see using 5W20 over 5W30 reducing your engine life by 30%.........I mean how many old RAMs do you still see, I know I still see lots and they are the ones with plows on the front, and/or towing huge trailers.
Just my two cents.