Oil in the coolant and vica versa looks a lot like a chocolate milkshake. You will normaly see it on the cap of the oil fill.
Prices vary depending on location. The best advice is to get estimates from reliable shops. Read the link entitled "Avoid Car Repair Rip Off" located in the blue box to the left of this post.
Good luck and let us know. :)
Sunday, April 15th, 2007 AT 8:47 AM