I ask because I am wondering if someone may have poured brake fluid into the coolant overflow reservoir. The color in the reservoir is a very dark red and there is a beige thick slimy substance mixed in that is coated all over the rubber \ntube in the reservoir. The level of the reservoir is well above the full mark when it wasn't previously. The engine oil and transmission do not appear to be contaminated with coolant. The truck was recently serviced with a front end brake job and brake fluid flush. The gunk in the coolant overflow reservoir was noticed after the brake job and brake fluid flush. The truck runs normal. Temperature stays in the exact range it has for the past 13 years. Oil level and transmission level have not dropped. The rubber tube from the radiator cap to the overflow reservoi\nr is noticeably swollen and elongated. This is a 1998 Toytoa Tacoma. Any information will be appreciated.