Grease is not messy unless WAY too much is applied. When properly applied grease is actually neater than oil IMO cause it can't run into places it's not wanted. On most guns I don't think it really matters which you use. Don't feel like your gun was being excessively worn from using only oil.
Yep, if you can see the grease, you've used too much. Never recall using grease in the military... used LSA before CLP.