Freeing a seized R16

[greydog]

I'd wire brush the joint between the piston and the cylinder and shop vac as much of the rust as possible out.
If you haven't pulled the crank, I'd let the ATF soak overnight. A little diesel will help the atf penetrate.
If the car can sit on it's wheels, I'd get a neighbor and with the car in second, me at the front and him at the back, rock the car back in forth.
There should be enough play in the drive train to just get the car to sort of rock back and forth. Keep an eye on the pistons as you rock the car. if they still don't move after a minute or so, let it sit again, maybe over night and try again. If you can get the pistons to move a littel, you can clean more of the rust out as a couple of the pistons move down away from the rust. Then move the car the other way and, again remove as much rust as possible. By that point, you should be able to turn the engine over with a ratchet on the crank bolt.
If still no luck. use JT's suggestion and start knocking out the pistons.
Good luck.
Dan

[cole455]

ATF and acetone (vigorously mixed together before applying)!

If still no luck, and cylinders are parked in a position for removal, I’d go JT’s route with a drift