Brake cleaner by itself will take 2-3 times to clean out oil from the cavities.
Does help if you cast 2-3 pours between spray/scrub.
I clean with Dutch Cleanser first, boil in Dawn, Rinse in Boiling Water.
Quick dry with Propane torch.
Then scrub with Brake Cleaner.
Smoke Cavities and go.
Just depends on how much work you want to put into cleaning your mold.