[greasltn]

The gunk in your intercooler is a mixture of oil (from the turbos) and water (from condensation). Both are normal, but usually you don't see much unless you really work the heck out of the turbos, or have tons of miles. You might want to mention it to the service manager when you go in, just so they can make sure you haven't blown a seal on one of the turbos.

 

[greasltn]

bendkodiak.

Not similar at all. The rusty color sludge in your overflow tank is where the coolant is reacting with the aluminum and steel in the motor. You need to do a coolant flush to try to get all of the old stuff out of the system, (motor, radiator, heater core, everything). When you refill, don't use the extended life coolant, use the regular green stuff. I would have been leery of buying a truck that has been driven less than 4K a year.

 

[greasltn]

Coolant has a slick oily feel, nothing to be concerned unless you see black oil droplets floating in it. A few different companies make cooling system flushes, they are all about the same. Just make sure you run everything out until it's clear, you will still not be able to get it all out but you should be able to get most of it. Don't forget to drain the block to get the last of the junk out and don't freak out if something looking like sand comes out. When you fill it mix your coolant 50/50 with distilled water and you should be fine. Good luck