All during the warranty period of 4 years it was set for 1 year and they did it every year, but the 4th and final oil change before the warranty/maintenance was out, it said 2 years later it was due but I verified with the SA and people here and they said it's once a year and I did it. After I got the car back the idrive said another 2 years it's due. I don't know - everyone says 1 year, and I mean everyone. Even if you only do little mileage - I've got 30k miles after 4.5 years.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr