My 2nd O2 sensor is STILL bad. They just ordered the part last week so I am taking it in tomorrow to finally get fixed. Well I was wondering, is that the reason I am getting much poorer gas mileage? I just filled up today and I got 260 miles to my last gas tank of 16.4 gallons. That averages to just over 16 mpg... not good!

When I have my A/C on, does the compressor shut off above a certain RPM? I know that it can damage the compressor by flooring it with the A/C on. I want to know so that I don't demolish my compressor! Also, how long do you think that compressors last on average (made in 1995). I live in an average climate where the temp is almost always between 50 and 85, So Cal. Thanks guys.

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)