The cylinders appear to be white simply because they are unpainted. As yet i haven't had time to paint the underframe, wheels, cylinders, etc.
I use the SEM etch primers and i am very happy with the results.
My mix is 1 part etch grey, 3 parts etch black, and 4 parts metho, mixed so the consistency of the paint is similar to low fat milk. I'm currently using a Badger airbrush.
Hope this helps.