Hello,

I was talking to a friend who has a 300C and says he runs 87 Octane, or sometimes will run 87 with a octane booster in it, is this ok? The manual says to run 89, is there any problems that would come from this.

Thank you,

 

It's obviously his car, but I would not use 87. The manufacturers are typically stretching when suggesting grades (try to use most economical), if it says 89, should use it.My understanding is the computer will de-tune motor to compensate for lesser fuel octane, but will it prevent detonation, which is the real issue? I don't think it is worth the risk or degraded performance for a few cents a gallon...