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Steve, BMW Expert
Category: BMW
Satisfied Customers: 23689
Experience:  BMW Expert
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I have a problem with my 2009 bmw 528i. I usually get about

Customer Question

I have a problem with my 2009 bmw 528i. I usually get about 360miles on a tank of gas in the summer, but in winter my miles go down by about 100 miles per tank .Now I know that they do have a winter blend, but seriously 100 miles. I wonder if when they
replaced my heater core last yr if the put the correct thermostat in car or if the even put a new thermostat in car. I dont know what the operating water temp should be and I could not find water temp in owners manual.I think Im on the right track with water
temp. Does anyone have any ideas? Thanks.... Adam Turok
Submitted: 1 year ago.
Category: BMW
Expert:  Steve replied 1 year ago.
Can you please clarify what type of ideas you are seeking? Do you want to know if the temp could be the cause?
Customer: replied 1 year ago.
Steve....I think the operating temp is the cause of my decrease gas mileage. So in the winter my gas mileage is decreasing considerably. I dont find in the owerners manual what my engine coolant temp should run and I cant seem to get a read out on the dash for operating temp. Can you tell me what my coolant temp should run? Is there a way I can get a read on my dash? Im pretty sure that coolant temp has a big bearing on my gas mileage. I know you helped me a couple of yrs ago with my heater core and you gave me great info. It was still under warranty.
Expert:  Steve replied 1 year ago.
Please do not forget to CLICK ON a positive rating
temp or a faulty temp reading could cause poor gas mileage.
it should run about 200-225f
since the sensor could be bad you should get an external reading, not rely on the car's reading
the best way to diagnose an issue like this is to have the car hooked up to a BMW scan tool to monitor all engine inputs and outputs to identify what is out of spec. The cost of this type of diagnostic is well worth it to avoid guess work and 100mi tanks of gas.
Please do not forget to CLICK ON a positive rating