Just clean it up real good with some degreaser are some good cleaning chemical then wash it off good. Use a good metal high temp primer and then a auto high temp paint and u should be fine. Make sure you post some pics when done.
Wow it just took me like 2 hours but i read through this whole thread alot of good info. I think my GM-3 is on its way out so I will be looking into this as a option. Glad the DP has gone to crap so i looked around and found this site.
I use Amsoil and have been very happy with it switching from rotella. Helps the old 6.5 build oil pressure quickly when its cold outside so i doesn't sound like its going to blow up.
I am here since it seems to be the place that all the 6.5 DP people are heading to. I think i am going to stay on untill it really gets bad if it does.