Originally Posted By: edwardh1
If a car NEW uses 5w 30, when it gets say 110,000 miles on it should you put 10w 40 in it? to compensate for wear?
seems there is SOME wear in 100,000 miles.
Ten to fifteen years ago, maybe--as a general rule. Now, not-so-much, unless there has been a history of lack of maintenance, severe service, excessive consumption, etc.
That being said, almost all "high mileage" oils are thicker at temp in the same grades, which is why I would only ever use one in the warmer months...