I just picked up a old Snuff can full of old grease fittings all different sizes and packed full of smelly old grease. I dumped them in a glass jar of kerosene and let them soak for a week they came out great, now I have lots of replacement nipples and they aren't the cheap 1 dollar variety that twist and break when you install them.

1950 Chevrolet model 1434 5-Window Canadian manufactured 1-Ton with Dump Bed / Hoist
In the Stovebolt Gallery
Follow the story in the DITY Gallery
You will never stop learning new things, no matter how old you are.