Question: Why should my cooling system be replaced between 80,000-90,000 miles?
Answer: With summertime temperatures in the Phoenix area often reaching temperatures of nearly 120°F for weeks at a time, the rubber and plastic components under the hood of your BMW are under significantly more stress than at temperatures even 20°F lower. This added heat stress is especially hard on the components of your BMW's cooling system, nearly all of which are contructed of the same plastic and rubber. When you have a component of the cooling system fail due to heat stress (which is very common in this climate), chances are the rest of your BMW's cooling system system is not far behind. Since the failure of any of the cooling system parts while driving virtually guarantees getting stranded and having your BMW towed into the shop, replacement of your cooling system is the best way to avoid coolant-loss related break-downs.
Question: When my BMW was being serviced by the dealer, they recommended a 12,000-15,000 mile interval for oil services. Why do you recommend a 6,000 mile oil service interval?
Answer: When we first begin to service a car that has been under the BMW service plan, more often than not we have seen an extreme build-up of sludge inside the engine, especially on the valvetrain components (see pictures below). While 12,000-15,000 mile intervals may be more acceptable in a cooler climate, higher ambient temperatures in the Phoenix area cause the oil to degrade at a much quicker rate. This degraded oil will solidify into sludge much quicker than clean oil. A 6,000 mile oil change interval will keep your BMW's engine clean and well-lubricated for years to come.