I changed my diff fluid out today with Royal Purple and a 4oz. bottle of Ford Friction Modifier. I ended up putting 2 qts in as bairly any fluid started to come out when I was topping it off. It calls for 3.2pts which is almost 2 qts. Just wondering, is it even possible to over service it? I would think not as the fill plug wouldn't even allow you to. Just curious since not a lot of fluid started to drip out when I was filling it up with the last bottle.