Actually, an MB tech recommended the mid-range for my 103 engine some time ago. He said that the onboard computer would adjust with these engines, and that 87 octane would work just fine as well. He simply preferred the mid-range, 89, octane. He also said that in the early days of the 103s, whenever they would run into a rough idle problem or a performance problem that they could not figure out, the MB rep recommended running the lower octane fuel because, for some reason, they ran better on it.

Joe B.