Quote:
Originally Posted by redpoint5
I don't know how much of a unique problem this is with Prius, but I doubt oil change interval has much to do with it. I've checked my oil condition with yearly changes and it was still well within spec.
The unique thing about the Prius is that it's designed to run the engine at high load continuously, which puts more strain on everything. If excessive wear is a problem with the Prius, I would suspect the cause is high loads and thin oil (0w20).
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It's much more complicated than just "engine runs harder", but frequent oil changes seem to prevent the problem all together.
First, these cars have low tension rings. Add to that the oil relief passages behind the oil control ring are small. When those passages and the oil control ring get clogged the piston now turns into an oil pump that pumps oil up into the cylinder.
One solution is to change the compression rings out for high tension rings. That way they always force oil through the oil control rings and relief passages as they scrape down and not up into the cylinder. But then there goes your efficiency because now there's more friction.
Another solution is to take the pistons and drill out the relief passages so that it's less likely for them to clog.
Or just change your pistons and rings every 100,000 miles or so.
But the easiest solution is to just change the oil by the manufacturer's true recommendation. Oil gets dirty and degrades over time and miles. So keeping fresh oil in the engine prevents deposits which prevents oil relief passages and control rings from clogging.
However, it seems like a lot of people change their oil yearly, if that. So they go 15,000 miles or so between oil changes when the manufacturer recommends yearly or every 10,000 miles
whichever comes first under optimal conditions. But the thing is that very very few drive under optimal conditions. Optimal conditions are summer weather flat road trip conditions. If you drive short distances, over mountain passes, in stop and go traffic, you're a trailer
OR in cold weather the real oil change recommendation is now every 5,000 miles or 6 months, whichever comes first.
The problem is that there is now an epidemic of oil burning Toyotas with less than 200,000 miles because hardly anybody changes their oil by the manufacturer's true recommendation for the driving conditions. And at the same time there's a group of people that have nearly half a million miles or more on their Prius or other Toyota because they've changed the oil faithfully every 5,000 miles (or 6 months, whichever comes first).