Toyota ever fix the 1MZ oil problem?

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Did Toyota ever fix the 1MZFE "oil gel" (sludge) problem? Ex, did the 2002-04 continue to be susceptible to sludge? I've never owned one. From a sample of one friend's 04 Sienna, I see the 3MZ does not have that problem. But did the 1MZ ever get fixed, or did Toyota produce it for eight years with that flaw?
 

BearZDefect

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Looks like Toyota made the 1MZ for ten years. Surely they fixed the "oil gel" issue at some point. BITOGers who know Toyota well, do you know? I don't want to call you out. ;\)
 
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Based upon the actions of the company in offering extra wty and repairs, I'm virtually certain that the remedial actions went into production with the 2002 MY engines. I've heard a couple variations of the explanation, but as best I can tell, they revised some oil passages in the engine, and probably improved the PCV system too. I would also imagine (no proof of this) that they revised the ECU programming with the idea of bringing operating temps down somewhat. I notice with some irony that it's rare for me to be able to coax my Camry hybrid's coolant temps above 200F (as reported via my SG-II). This is notably cooler than many domestic engines, which I understand run between 220 and 230F. When cruising here in the Florida summer, I see 185-195F. Might mean nothing, but who knows... EDIT: the afflicted I-4 engine, the 5S-FE got no improvements. It went away with the intro of the 2AZ -- in 2002.
 
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BearZDefect

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ekpolk, you're the best. Thank you for the details. I realize the 2.2L 5S-FE went away. Besides being harsh on oil, it was too weak for the next generation Camry.
 
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 Originally Posted By: ekpolk
....they revised some oil passages in the engine, and probably improved the PCV system too.
Thanks for the interesting info. Question, though: Was it the oil passages or the coolant passages that were revised in the fixed engines? I thought it was the coolant passages since it's believed that Toyota made the coolant passages in the bad engines too small when Toyota was trying to improve their CAFE numbers.
 
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They may have improved the 1MZ-FE, but even the later 1MZ-FE engines are very hard on oil.
 
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