We can buy a quantity of six filters for the 603 or the 617. These are sold by Champion under their "Luberfiner" division, however, they are purchased from somebody else.

These are the same filters that Baldwin purchases.

The local distributor is:

All System Brake
Telephone: 631-491-4000
Contact name: Joe

Part numbers:

603: P829
617: P825

Pricing:

603: $12.47 plus shipping (you must purchase six)
617: $12.42 plus shipping (you must purchase six)

Could not get the pricing down into the $11.00 range because of insufficient quantity.

You might be able to get similar pricing from a local distributor of Luberfiner if you can find one. It's not easy.