Comment Re:The old auto makers are fucked. (Score 5, Informative) 252
It's really quite simple if you've ever gone elbows deep into a modern engine...
To meet new CAFE numbers, you have to get your engine as small and light as possible for the parameters it needs to meet for the product. So, all aluminum 3 or 4 cylinder blocks, under 3 liters of displacement. These don't produce great power naturally aspirated so you add some form of forced induction. Turbocharging tends to be the most efficient and easiest to control to provide variable boost so you bolt one of those on, with all the plumbing and controls.
Forced induction leads to higher chamber pressures. Add direct injection and you start getting some rather "dynamic" effects during combustion. All this energy gets transmitted down the conrod to the main crank. What's protecting the crank? Soft metal bearings that expect a certain amount of oil film of a certain strength to be between the parts to cushion, cool and lubricate the crank and conrod.
Thanks to other parts of CAFE and EPA regulations, the oil specified by some engine manufacturers is light...very light. 0W-20 or even 0W-18. And, it has fewer "old school" additives like zinc sulfate or similar, that act to protect against metal to metal damage, should the oil film get too thin.
Finally, your average car owner in the US is not the best when it comes to maintenance and will run an engine long past its oil-change point. This is where the trouble starts. These thin oils don't have great additive packages because they have to be thin to keep the lubricating friction losses down to meet efficiency benchmarks. As the engine racks up hours they tend to overwhelm the oil detergent packages (detergents suspend fine particles swept up by the oil, hopefully to be filtered out) and start shedding ash and other particulates. At this point, the oil isn't meeting the lubrication requirements, and you start seeing bearing damage. Keep this up and eventually you'll trash a bearing as everything's been engineered down to the Nth degree with little margin for slop.