Although this can't always be relied upon it is usually correct. A leak of automatic trans fluid into the radiator usually leaves a pinkish color, engine oil usually tan, dark brown or black. Check inside the coolant reservoir that connects to the rad by the rad cap. Because there is 'air space' in there, an oily scum or film will float and also leave a scum line, it's easier to see the color.

Another clue may be if the trans fluid keeps going low and no external leaks are present.

It's pretty important to narrow down the source of the leak at least to Engine or Trans, from there diagnosis gets a bit easier. Otherwise, it's still a guessing game...

I drove my '86 Dodge van, 318cu.in. (5.2L), over 300K miles. It had a cracked head at about 200K (causing oil in coolant), but that was not real difficult to replace. Check/replace valve-lifter rods while you're at it, too. They are really long and bend around the decade mark.

Edit: When I started having trouble with the radiator (fan clutch, leaking, bad hoses, etc) the engine got overheated and improper addition of coolant caused cracked head (I added water when it had boiled dry). Advice about transmission fluid mixing in the radiator is not even a possibility (the cooling coils are separate). Also, head gaskets on the 318 are bullet proof, but will need replacement when you replace the head, and you can do it in your driveway with parts from Auto Zone or Napa for about $500. http://www.napaonline.com/ShoppingCart/s... Unless you want to replace both, do a compression check to find where the crack is.

Reaching almost 150 K miles? Here's what I experienced:

20 K: drive-shaft universal joints (originals were junk! Never had a problem again).

150 K: fan clutch replacement (worn fan clutch makes a rumbling noise), radiator, head and gasket (left side only), valve push rods (both sides),

200 K: transmission replacement, timing gears (original were nylon gears, and I replaced them with steel)

250 K: air-pump ("smog" pump) tube ruptured at exhaust manifold, radiator hoses (all, including heater hoses) replacement, steering gearbox.

I did most of this work myself in my driveway, except for the transmission. Get a Chilton manual.

Thats the thing, i cant determine the problem, but i can fix it once known, so only paying for parts! Thankfully. Im jusg hoping its just head gasket and not the transmission cooler in radiator or intake gasket.

Transmission cooler in radiator could be leaking fluid into coolant if the radiator is bad. Why would you rather fix a head gasket instead of replacing the rad???

Most likely a failing head gasket, do a compression test to confirm that.

Sorry to hear that, head gasket replacement is not cheap.

Ok, i have a 2003 dodge ram 1500 v8. Theres a little oil in my coolant. Im trying to order parts, but dont wana waste money. I do have a cracked radiator,that im replacing,if that has anything to do with it. I was thinking head gasket. But please correct me if im wrong.