Same Bearing Clearances but Different Oil Viscosity and OCI for 1GR-FE Engine

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very smart people found out unless HTHS falls below the mid 1s nothing happens. this is how 0W8 became a thing

the tacoma motor was made in alabama and the fj/4runner engine is made in japan. the latter probably changed over their factory fill first with secondary fuel economy benefits
 
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ZeeOSix

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very smart people found out unless HTHS falls below the mid 1s nothing happens. this is how 0W8 became a thing

the tacoma motor was made in alabama and the fj/4runner engine is made in japan. the latter probably changed over their factory fill first with secondary fuel economy benefits
Source: https://www.q8oils.com/automotive/low-hths-oils/

Shows different engine component wear rates vs HTHS viscosity. Rings (very hot zone in the engine) seem to be the component that wears the most with low HTHS oils, and I've seen other sources show similar info.

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S
 
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Toyota recommends 0W-20 with an OCI of 10K for a 2011 4Runner with a 1GR-FE engine.
Toyota recommends 5W-30 with an OCI of 5K for a 2010-2013 Tacoma with the 1GR-FE engine.

I looked up piston ring set, crankshaft, connecting rod and main bearing part numbers for the 2011 Tacoma. Most of those parts show "also fits 4Runner" or have the same part numbers. Only 1 out of 15 bearing sets has a different part number between the two vehicles. Both engines are dual VVTi. Oil capacity difference is 1.1 quarts for the 4x4 vehicles.

I'm wondering why a difference for the recommended OCI and viscosity. Any ideas?
Toyota recommends thicker oils for this engine overseas, as several have mentioned. Temperature dependent of course. I ran 5w-30 in mine before I had to sell it, UOA was great and no loss of mpg or power. Had 5w-40 on the shelf ready to go for next change. Stupid pandemic.
 
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True; 4Runner and FJ got dual starting 2010.

Not only that but the Dual VVT-i 1GR-FE, also has a different block with improved cooling, a different crankshaft, pistons, cylinder heads (Dual VVT-i has roller rockers and hydraulic valve lash adjusters), different intake and exhaust.

The better cooling and lower friction in the valve train were the primary reasons allowing the use of 0w20. But as also noted, the Dual VVT-i 1GR-FE is speced for up to 20w50 in some markets. Our (USA) 0w20 spec is mainly CAFE and EPA driven.
 
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