The old hammer and chisel routine has worked well for me dozens of times. You need a big hammer, sharp chisel, and aggresive blows from the hammer. Of course I have always had the convenience of a hoist. That makes the job easier.
PS: Now might be the time to invest in an oil sucker. The car was designed to have the oil changed that way. That dipstick tube goes to the very bottom of the pan.
Auto Zentral Ltd.