strange MPG loss

dwp-wa · 05-29-2009, 01:27 AM

My oil/filter changes never work out the same as other services. Just before 15,000 miles, the MPG went down to 28 MPG, and back up after service. I have the 30,000 miles service next Monday. After I had the oil changed last month, my MPG dropped from 44 MPG to 32 MPG. The dealer swears they do not cause this, but it sure looks suspicious.

ceric · 05-29-2009, 03:49 AM

Some people are more careful. They disconnect the (-) terminal of battery to avoid getting shocked or shorting the circuitry. It is probably a good practice. However, that would probably send the computer setting back to factory setting. Whatever, the car has learned from you or you have trained it is gone.
Disconnecting the (-) is a command way to get settings back to factory. Same goes for changing the battery unless you use a parallel battery when replacing it.

richard schumacher · 05-29-2009, 06:42 AM

Do you check the oil level yourself immediately after the service, before leaving the dealer? A severe overfill can reduce MPGs (and everyone should always check anyway, to find gross errors).

How often do you check tire pressures?

05-29-2009, 01:27 AM	#1
dwp-wa Junior Member Join Date: Mar 2005 Location: Auburn, WA Posts: 26 My Car: 2005 Prius Model: Package: Base Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	strange MPG loss My oil/filter changes never work out the same as other services. Just before 15,000 miles, the MPG went down to 28 MPG, and back up after service. I have the 30,000 miles service next Monday. After I had the oil changed last month, my MPG dropped from 44 MPG to 32 MPG. The dealer swears they do not cause this, but it sure looks suspicious.

05-29-2009, 03:49 AM	#2
ceric Senior Member Join Date: Oct 2004 Location: Fremont, CA Posts: 1,040 My Car: 2005 Prius Model: Package: #6 Thanks: 0 Thanked 43 Times in 16 Posts Friends: 0	Re: strange MPG loss Some people are more careful. They disconnect the (-) terminal of battery to avoid getting shocked or shorting the circuitry. It is probably a good practice. However, that would probably send the computer setting back to factory setting. Whatever, the car has learned from you or you have trained it is gone. Disconnecting the (-) is a command way to get settings back to factory. Same goes for changing the battery unless you use a parallel battery when replacing it.

05-29-2009, 06:42 AM	#3
richard schumacher Destination: Eschaton Join Date: Mar 2004 Location: United States Posts: 5,510 My Car: 2004 Prius Model: N/A Package: #6 Thanks: 99 Thanked 93 Times in 66 Posts Friends: 0	Re: strange MPG loss Do you check the oil level yourself immediately after the service, before leaving the dealer? A severe overfill can reduce MPGs (and everyone should always check anyway, to find gross errors). How often do you check tire pressures?

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