Another vote for Odorless Mineral Spirits BUT, I'm pretty sure but not positive, that all the plastic pieces in your cleaner will be OK so hopefully one of the resident chemists will chime in. OMS will cut through chain gunk better than any water based cleaner and can be saved in a jar so that the gunk settles to the bottom and you can just pour off the clean solvent to be used over and over again. This is more environmentally friendly as well since you're not pouring gunk filled used cleaners down the drain or into your garden.