I Have 2010 tundra with 160,000 miles.4.6 I have always used OW 20 oil Not always the same Brand…I have some OW 16 oil , can i mix say 5 qt of Ow 20 & 3 qt of Ow16 At oil change
I don’t know if you have to add oil between oil changes but would it not make more sense to use the correct oil and use the 0 W 16 to keep the level full . Good grief just how much money are you going to save anyway ?
In my limited experience older, higher mileage engines need heavier oil rather than thinner oil. At 160,000 miles I’d stick with 0w20 in your Tundra. Out of curiosity, why do you have 0w16 lying around and do you have another vehicle that can use it?
I would stick with what the vehicle requires. Here, I looked it up, this site usually matches the manual, I use this oil for my Impala. I also used it for a previous Toyota Camry that had oil consumption issues and this stopped it so it is a top oil. You can benefit from the extra protection with the miles you have on your Tundra.
https://www.searchforparts.com/oil-change/toyota-2010-tundra-4.6l-1ur-fe
The engine in your truck has variable valve timing.
The variable valve timing can be effected by the oil viscosity.
If the Check Engine light comes on with VVT codes, switch back to the oil recommended.
Tester