Checking oil level

Don't the markings on oil dip sticks mean anything anymore? In the case of the last three cars that I have had experience with, if the specified amount of oil was added during an oil change, the oil level would be over the mark for the maximum. I just bought a 2012 Mustang premium convertible. I checked the fluids and, sure enough, the oil is well over the maximum level. It was once thought that running a car with too much oil is hard on the seal bearings. Is that still the conventional wisdom?

Being new, it's hard to check the dip stick with synthetic oil.
I put my money on the dealership doing the bad!

interesting that you say the last 3 vehicles
marks are for reference- between the 2 lines is usually good

are you saying your last 3 when you changed the oil/filter and added as your owners manual said for your particular engine your dipstick was way off- some want it exactly at the full mark, some want below the full mark- if finiky slowly add the last bottle checking a bunch

seen a few where 2 quarts over full moved the main seal-

A vehicle should be a normal operating temperature when you drain the oil , but really it should be allowed to sit for a few minutes before draining to allow the old oil to drain back into the pan . This isn't the case at the the quick change oil places ( likely the dealers may fall into this as well ) . If it isn't given sufficient time to drain back and the new oil is quickly added , you're likely to overfill the engine stated capacity by some small amount . Quick service is their intention and ( unless your engine is using oil ) , the extra oil left in the system will continue to build up through succeeding oil changes .

When you change the oil, as the poster above said usually not all of the oil is actually drained because the car is not allowed to sit for a while after the main flow of oil stops, this is an issue because over time excess old oil builds up. If you're filling your car to the engine's actual capacity, that plus the old oil could equal too much oil :-)

make sure your checking it on a level surface. stick it a few times as the stick rubs the sides of the tube and can give you erratic readings. the proper way is to remove the oil plug then remove the filter. this prevents any filter drain back into the crankcase. reinstall the new filter and then install the oil drain plug. the plug shouldnt have to be out longer then it takes to r&r the filter. also make sure again your on a level surface when changing the oil. i like to fill it up closer to the max fill line than in the middle.