IMHO Redline D4 ATF (bit expensive but lasts). Lot of owners have been running this for years, me included. Long term testing against filter and magnetic plug deposits suggest it may be one of the best.

For Air-conditioning systems. Apart from filter replacement, Valvoline make an AIR sanitiser that kills Mould, Mildew and odour causing Bacteria throughout the entire ducting system. Simple to use and takes about 4 minutes. A must for anyone with allergy's.