[macgyver]

Don, you should disassemble the slack adjusters and completely clean out the old grease. Use a bentonite clay based grease when you put them back together.

http://www.mcmaster.com/#clay-thickened-grease/=1292gqn

The reason for the clay base is to withstand the high temps that the adjuster might see.

Thanks Richard , I'm glad to hear that they should be serviceable the Joker at the shop didn't think they were! I'm quite supprIsed that an 87 even has automatic slack adjusters !