I noticed a leak of greenish grease near the inner part of my (passenger side) cv halfshaft of my 1997 Blazer. Is this leaking from the CV Halfshaft itself or the front differential? I imagine the front differ. would just be a seal, but the CV would need to be replaced, about the same amount of labor either way.

If it is the CV halfshaft, how soon should I replace it?

 

Green grease == CV shaft leak.

The front diff has regular gear oil inside.

You may be able to get away with just replacing the boot (no 2 piece boots though), but without the crimp pliers, it is difficult to get it clamped back on. The easiest thing to do is replace the CV shaft.

I would not drive it very much before replacing it though. If it wears the CV shaft too much, it can come apart on you.

 

you can rent or buy the crimp tool at most auto parts stores.