The coolant in our overflow tank is a very dark color almost black. It is a 2011 EcoBoost and has 58,000 miles. I know when oil mixes with coolant it turns into like a foamy looking milkshake. This is not the case. It is just very dark. I don't know about inside the radiator since It does not have a cap.

 

You are still on powertrain warranty, I'd get it to a dealer to be checked out.

 

Afraid what they might find and we bought it used so I have no documentation of prior maintenance... I will take it in Monday morning.

If it is something major and warranty denies it...will they charge me just to look at it?

 

Depends upon the dealer and your relationship with them. If you have been going there forever, most likely they will have a quick look for free. If you are some random person off the street, less likely.....

 

It shouldn't matter how it was maintained in the past, because there is no maintinance required on the cooling system in 58K.
If it was programmed and ran hard in it's first life, then that could make a difference if they can prove that is what caused its issue.

I have a hunch, it could be a head gasket leak. If exhaust is getting into the coolant, it could be turning it dark.
The other thing is there could be a leak in the tranny cooler in the radiator and getting trans fluid in the coolant. That would be a much better issue to have.

Good luck and let us know what the dealer tells you.

 

Call the dealership first and ask.