Yes, another thick vs thin thread, but this one's a little different. Let's take my car for example (just to make it simple), it specifies a 5w-20, 5w-30 or 10w-30. Let say I decide to run a 5w-40 or even just for discussions sake, a 15w-50 oil for the life of the engine. No VVT codes or other strange things happen, and the vehicle is always started in warm weather (we'll say no colder than 72°F). Is there any mechanical or scientific reason that running a thicker oil could cause increased wear?