Re: oil in coolant? DIY help
If your coolant is in fact bad, you'll see chunky white residue around the inside edge when you remove the pressure cap. If your engine oil resembles chocolate milk, then the fluids are mixing. There are so many colours of coolant out there, I don't remember if they make a brown! Cheapo coolant these days easily lasts 60K before a service is required. In some cases, a shop can flush and filter the current fluid as long as it tests OK. It saves money. In your case, it'd be worth while to get a good diagnosis to make sure your head gasket is OK before replacing the coolant, for if the head gasket is bad, the coolant will be evacuated and replenished again anyway.
I'm sure someone will chime in as well on this, but once the vehicle has cooled down you'll have to remove the lower rad hose, then remove the pressure cap. I don't have a diagram, but along both sides of the block there are bolts to allow the fluid in the block to come out. You'll also have two hoses going into the firewall, they supply your heater core. It's best to backflush the heater core, even with a garden hose (there are kits out there to do this somewhat easily, even for a DIYer), this will remove any built up rust inside to prevent failure down the road.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!