91 Octane or higher. The first time my wife took the X5 for a drive she put 89 Octane and the engine light came on, the X5 drove rough the whole tank!

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2010 X6 50i
2005 X5 3.Oi, Many Options
2015 HONDA CR-V EX-L
1998 ACURA 2.5TL

MODs
- Driver's outside mirror light
- Voice Recognition Module
- Blaupunkt Entertainment System
with Digital TV