Agree, change the oil every 7500 miles. The BMW 15k mile change interval is totally crap IMHO. The problem is oil contamination. Many of these engines run too cool due to soft thermostats and/or are driven too short of a distance.

It takes 2 to 3 times longer to warm the oil up than the coolant. If the oil does not get fully warmed up the water and fuel contamination does not get cooked out of the oil.

Living in Colorado, I would assume you deal with cooler weather often. I also recommend starting out the Winter season with a fresh oil change so you have clean oil that can handle more contamination.

Fresh oil can be contaminated in as little as 1000-1500 miles if the engine is running too cool, not driving long enough to warm up the oil and the weather is cold.

As they say, oil is cheaper than steel!

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2008 4.8i Black with Tabacco. Black Y-spoke wheels and shadowline trim.