How much break fluid do i add on a 1956 olds 98 dip stick has no marking?

For a 1956 Oldsmobile 98, brake fluid is typically added until it reaches the full level in the master cylinder reservoir, rather than relying on a dipstick. If there are no markings, check the owner's manual for the specific reservoir capacity or fill to about 1/4 to 1/2 inch from the top when the vehicle is level. Always use the recommended type of brake fluid for your vehicle, and ensure that the system is free of leaks before adding fluid.