What to do about excessive oil consumption in GM cars?
What to do about excessive oil consumption in GM cars? The engines have aluminum or cast iron blocks and are equipped with active fuel management systems (AFM). The fix includes installing an AFM oil deflector and cleaning carbon from the cylinder head. Why does my GMC Envoy have high oil consumption? This bulletin does not apply to the Buick Rainier, Chevrolet TrailBlazer and GMC Envoy equipped with LH6 due to a different design oil pan and AFM pressure relief valve. On higher mileage vehicles (30,000-40,000 miles) you may notice high oil consumption along with a service engine soon light on...