What is wrong with my brakes if I can not bleed them? on 1999 Ford F-250 Super Duty

I change out the master cylinder, all calipers and the rubber hoses that go to them. A mechanic told me that someone must have put something petroleum base in the system due to the rubber seal on the cap swelling. No no fluid will move through the system when I pump the brakes and try to bleed them.

if oil was installed poss other parts are damaged