Aw heck...I cant call the name of it now, but I use a 4 wheeler chain lube.  I used to race quads, and when I quit I had quite a bit of 4 wheeler chain lube left over.  Come to find out it was, without a doubt, the best Ive ever found..

 Sorry I cant call the name of it right now, but it being quad chain lube ought to help if you wanna look into it.

 BTW: Speaking of 4 wheeler chains, it makes me think.  I used to race very high hp quads, and I always used a 0-ring or x-ring chain.  the x-ring had less drag than the o-ring.  I dont know why some of the main chains on these planters are not o-ringed; thereby greatly reducing the need for ANY lube !!!

Next time I have a chain go out (my planter is only a year old), I am going to try and get an o-ring chain, at least for the transmission chains.