The only part of the RD you would use grease in would be, maybe, the lower tension-roller - that's the bottom wheel on the RD. I think the top wheel is either sealed or ceramic. Not sure, so look and see. On the parts that move, including the spring, you want to use a top-quality oil. By the drop on the pivots. Just one drop on each moving part is all you want. Otherwise it will attract dirt and grease and everything from outer-space to slime it. After you've oiled it and run it through it's paces (manually at home - not on the road), you should wipe off any oil that is visible. Just use a clean towel and give it a good wiping.