I started using “vipers venom” but one day I ran out and needed to finish the job. I bought rigid dark cutting oil locally and finished the job. Since then I’ve stuck with rigid, I cant notice any difference in chambers, it’s considerably cheaper and available locally.
I’ve also read some guys using the rigid “nu-clear” with good results, and it’s supposed to be much easier on you. (No halogens, or other nasties)