I'm glad that you have finally, after an almost 2 yr saga, decided to up the viscosity.I'm not too concerned about engine wear - the car will likely be sold/traded before 200k anyway. Probably 150K.
Welcome to Bitog. There is a problem with sheering oil?What are Euro oils are called in Europe? Oil. A 5w30 over there is usually not the same resource conserving oil that will sheer out of grade as quickly. No surprise they are not running into oil consumption problems over there.
I was incorrect. Apparently, Toyota allows 10W-30 at temps above 0F on the 1MZ-FE Sienna:Below that is debatable. Some diesel applications allow a 10W-xx down to 0F, but I have not seen this recommendation for gas applications.
Oil catch can/oil seperator should not fail for visual inspection. As long as it is sealed and using the proper hose(s), not using a heater hose type. It should pass.We're pretty strict on smog in CA; I think any modifications to the crankcase vent system will likely result in a failure during the visual inspection portion of the test.