thank you

Does anyone know where I can find some good information about performing routine maintenance on diesel engines?  I have a bunch of Bachmann DCC (GP35, GP40, GP38-2) engines.  Some of them are staring to squeek when they run and are pretty loud.  When I took some of the the bodies off, I noticed there was little to no grease on the gears that turn the wheels.

I see Bachmann has a few EZ Lubes, should I be using Conductive Contact Lube, Grease or Light Gear Oil.  I'm not sure the purpose of each one and don't want to use the incorrect one and cause damage.

Also, what is the best way to clean EZ Track.

Any help will be appreciated.
Thanks