Over filling auto transmissions is a common problem. In most cases over-filling by 1/2 pint or less won't hurt, but whenever cars are driven for more than 15 miles & the trans reaches full operating temp then over-filling will cause foaming! Foam will not lube trans & will allow trans to slip. As Benzmac said the level should be at least 10mm below bottom line w/cold! On the older cars (before 1981) it should be 20-25 mm below bottom line w/cold. If the trans doesn't want to engauge reverse w/cold the the fluid level isn't the problem.
[This message has been edited by M.B.DOC (edited 04-30-2000).]