How do you check oil in 2001 Mercury 90hp 4 stroke?

To check the oil in a 2001 Mercury 90hp 4-stroke engine, first, ensure the engine is level and turned off. Remove the dipstick, wipe it clean, then reinsert it fully without screwing it in and remove it again to check the oil level. The oil should be within the marked range on the dipstick. If necessary, add the appropriate oil type to reach the correct level.