Although oil test companies have shown the oil viscosity to be fine at the recommended intervals I change mine at half the recommended intervals or at least yearly. My only reason is peace of mind. Oil is probably the most important component of the engine and the realitive low cost is good insurance. Actually the filter is probably more inportant as it is the particles in the oil that I would want to ensure are removed or kept to a minimum.

Based on the above I have had vehicles go to 350k km without buring a drop of oil between changes.

Also funny how BMW recommended intervals increased when maintenance became included.

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2008 X5 4.8i BSM/Blk - premium, sports with 20" 214s, navigation, rear climate, adaptive ride, dark bamboo, running boards, 3rd row seats, USB audio, high speed maximum, etc etc

Mods: Smoked reflectors | Hoen xenon match fogs and angel eyes | LED plate bulbs | 18" winter wheels

Other vehicles: 2002 M3 Vert TiAG/Blk - with every option and many mods | 2009 Chevy Silverado LTZ - fully loaded