If you are driving on the Autobahn @ 140 mph, it requires approx four times the Hp that it does at 70 mph. This results in much higher engine loads, and you can easily see sustained oil temps of 250F-270F. This is particularly true with an engine that's designed/geared like this Honda - it's practically a motorcycle engine.
An SAE 20w-50 oil running @ 250F will have approx the same bearing viscosity as a 5w-30 or 10w-30; running @ 210F. A 20w-50 running @ 270F will have the same bearing viscosity as a 5w-20; running @ 210F!
There's no conspiracy here ...it's simple High School Physics. [/QB]
1) Europeans and Japanese do not routinely drive 100+ miles per hour. Period. Their driving habits are actually pretty close to ours in America. In some places, at least in my experience, they drive on average much slower than we do on our highways.
2) Even if European vehicles see speeds like these, how often? All the time? Most of the time? No. What about the vast majority of the time when they're seeing far lower speeds, and hence lower, more "American-driving-habit-like" oil temps? They're still running much thicker oils -- much thicker recommended
oils -- than we are. Are their bearings somehow more or less forgiving than ours when running at the same speeds?
I'm afraid the conspiracy still stands.
I ask again, what happens on the way across the ocean? Do engine tolerances mysteriously shrink because of the ocean air?
I have no problem with people choosing to run thinner oils in their engines, but I can assure you that manufacturers don't recommend much thicker oils across the pond in identical
engines because of anything resembling concern about engine wear.