Is an over-filled engine oil bad? I've had my Mazda taken to the dealership for fluid replacement and each time I noticed that the oil level was above the second mark.
Yes it is bad. Engines are made for a certain amount of oil. If you put too much oil, it takes up space that wasn’t taken up before and can cause compression problems that can blow seals out.
You’d want to empty it out so that it’s just at the full level and go someplace else to get your oil changed, because will need to be at the full level. That’s what a pro does. I always look them up. I don’t even trust a gas sign. I look at my computer and if it says 3.4 quarts, I put 3.4 quarts. You want to be a pro when you’re changing it and not put the wrong amount in because it can ruin it.