I am currently running 0x30W Amsoil in my 2008 Tundra and I am wondeing if the 0x20W will be any better, in the 4.7 engine. The 5.7L engine runs 0x20W. Would I notice any benfits from running a little oil than what I m running at the moment.
Really should only use what the owner's manual says--at least during the warranty period. Probably don't want to second guess the engineers who set the bearing clearances, etc. on that particular size, year, and production run of engine. You can void the warranty. For example: Last year's same type engine may have even specified a different weight, but you have no way of knowing if they made subtle changes in this year's engine series for a new oil weight, or if it is the same engine as before with a thinner oil spec'd for fuel economy. Just my thoughts.
If I were you, I'd even 'step down' and run the 'XL' 5W-30 in your Tundra. It is still under warranty, and your manual will most likely call for an API-certified oil.
SSO 0W-30 isn't API-certified. I have no doubt it exceeds the requirements, but it isn't certified as meeting them. The XL line is. IF you have a warranty claim on this vehicle, and the dealer wants to see service records, and they see you used 'non compliant oil' even if it IS better than what is required, you warranty may be null and void.
Don't know about you, but i wouldn't want to lose the warranty on a year-old vehicle....that's a LOT of warranty to lose. It may not come to this, but WHY take a chance?
Something to think about!