Freeing a seized engine?

I have an 1800 slant 4 engine in a HC Viva, the engine has not been started for some time and its seized through lack of use, I have put some heating oil down the bores, well 1 & 3 as 2 & 4 are at the top, I done this around 2 weeks ago, how easy will it be to free the engine and can it be done by rocking the car in gear or towed please?