I got my coilovers last summer, i'll usually spray it down with soap/water at the coinop and then wash the rest of the car. After the rest of the car is washed ill spray down the coilovers from top-bottom with silicone spray lubricant.
Doing the above 1ce-2ice a week has kept them in pretty much mint shiny condition. When i took them off for changing the UCA and ball joints the threads were actually the same as they were the first day they came in a box.
What i've found is that antisieze paste tends to get all grimy and collect crazy amounts of dirt if/when applied on the threads
For me it was actually the other way. That lubricant didn't help at all, collected so much deposits that I had to take them off to clean. And I cleaned them and sprayed every week though they saw snow only once or twice. The grease in the other hand, didn't collect much, but if it did, you just take a paper towel and wipe them off and they are as new.