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Oil change frequency

on my 2008 cts…they recommend mobil 1, but some discussions on the freqency vary a great deal. do i go by the sensor life or just change it every 3000 or 6000 or 10000 or what? when i bought the car, the dealer gave me free changes for a year. and they said 3000 miles. however, they put in a blend. thanks for your help.

I’m amazed the dealer put in a blend, I thought the manual specified full synthetic. As for mileage, GM has a fairly intelligent oil life monitor, I’d go with it.

For the year, I would do the free oil changes. When it is my dime, I would go with Mobil 1 and be done with the speculation/uncertainty, and use the oil life monitor, per the owner’s manual instructions. Your owner’s manual should specify the exact GM oil spec that is required, and whoever changes your oil needs to make sure that the oil used meets the spec and is listed on the GM spec list.

My short research shows that most folks are using Mobil 1 because it is factory fill and the most recognized oil that meets the GM spec. It is possible that a blend meets the spec also, and that is why the dealer is using it instead of Mobil 1, for their free oil changes. The list I found was 2005 and listed Mobil 1, Havoline synthetic and Chevron Supreme synthetic only as meeting the GM spec at that time). Check out some Cadillac forums for more info.