I have a '93 Honda Del Sol that needs only about 3.2 quarts of oil on an oil change. But, when I take it for an oil change, EVERYBODY overservices the oil - some just a little, some just a lot. So, how much is too much? What exactly are the problems that can occur with overserviced oil?
If the oil is slightly over the maximum line, it is nothing to worry about but if it is too much over the maximum, it can result in loss of performance and excessive blowby pressure which is not good for the engine in the long run.
As long as oil level is within the maximum and minimum line, it should be good. However it must be noted that old engine tends to consume some il and if level is too low, you would have to keep tad more often to avoid oil running too low.