I switched my zetec over to 10w-30 at about 75000 miles and ran 10w-30 in her through winter and summer for two years. I tried 5w-30 in her but she hated it. Then I got in the wreck and no more zetec. She had 120,000 miles on her, 45,000 miles of castrol syntec 10w-30 and she had full compression on all four after the wreck (engine was still perfect cept for radiator and power steering).
Now I have this honda accord with over 180,000 miles. I switch over to castrol syntec 10w-30 and voila, perfect. The car runs like a dream, no oil leaks whatsoever and she no longer burns oil.
So whoever said you can't change engines with over such and such miles.... you're a liar!
