I'm not sure what is considered a "fundamental change", so I'll say this:
For an LX570:
**Engine Piston, Part No. 131010S011, fits 2008-2014
**Engine Piston, Part No. 131010S030, fits 2013-2021
**Crankshaft, Part No. 134010S010, fits 2009-2011 (there was no 2012 model year, IIRC)
**Crankshaft, Part No. 1340138010, fits 2008-2021, labelled as "interchangeable" with S010, as opposed to "superseding". I interpret that as meaning the 8010 part can be used in place of the S010 part, but the S010 part can't be used in place of the 8010.
You can do the same thing with all the Toyota 5.7L variants (Tundra, Sequoia, et al.). So, I'm guessing SOMETHING changed? Can you explain?
Maybe it’s nothing?
I guess there are two possible biases:
- 0W20 is WORSE for my 5.7L engine, and the ONLY reason Toyota Corporation specified is to appease various USA laws. The engineers begged management not to specify 0W20, but management decided after risk consideration that the use of 0W20 would result in more wear and tear, but not enough to noticeably sacrifice reliability or reputation.
- 0W20 is BETTER for my 5.7L engine, and the ONLY reason Toyota Corporation permitted other heavier weights in other parts of the world was to appease local availability and cost (or other variables). The engineers, although they preferred 0W20, decided after risk consideration that the use of heavier weights would result in more wear and tear, possibly some coking of the piston rings, possibly a little more oil consumption, but not enough to noticeably sacrifice reliability or reputation.
I’m guessing you are in the (1) camp?
STORY TIME
I’ll end with a story to contrast all the posters that read something like “
I’ve used 0W40 the whole time and ne’er a problem!” My first Lexus was a 1999 GS400 – the car that converted me to forever Lexus. I bought the vehicle at about 100k miles. I had a catastrophic engine failure at high RPMs at about 125k miles. Piston rod popped three holes through the block (and my steering rack!). While looking for a salvage engine replacement, I ran into the same response: those engines NEVER fail! One guy even informed me that this engine was one of very few car engines approved for use in an airplane. So I went back and looked at all the pristine maintenance records from the previous owner. And there it was: he always specified 10W40 Castrol at oil changes (~100k miles worth). Stupid me followed the OEM specification: 5W30 (10W40 was not an option). I always noticed I was almost a quart low every oil change, but I didn’t know any differently. Figured it was typical for an older car. After the salvage engine was installed, I kept the car for another 100k miles (engine ~200k total). Used 5W30 the whole time – and it was NEVER low at subsequent oil changes. And I drove the car at high RPMs, Texas heat, all the time. And it was black on black without window tint – can’t get any hotter!
Although I certainly do not know for sure, I speculated that the use of the heavier oil for such a long time caused the engine to “loosen” up. When I started to use the lighter OEM-specified oil, the engine pieces were able to move around just a tad more and eventually caused a catastrophic fatigue crack. Maybe not – maybe totally random and unrelated? But I’m not a big fan of coincident.
REQUEST
Those of you that decide to use the heavier weight oils contrary to your owner's manual, please (1) stick with it, don’t change later in life, and (2) please make it clear to the possibly younger, possibly poorer, next owner that they need to continue using the heavier weight oils.
Good talk. Thanks for staying respectful.