So I took my 2007 Prius in for the first oil change. It had just over 5000 miles on it. Another 1000 miles and 3 weeks later I have lost around 1.5 MPG. I was getting around 49 miles per gallon (and slowly increasing) and now I am around 47.5 (and rapidly decreasing). I drive the same route to work every day and take advantage of the electric motor. Usually through town I let off the accelerator and slowly press down again and then the electric motor takes over. I can do this anywhere from 30-40 MPH. However, since this "oil change" I find this "tactic" harder and harder to achieve. I can rarely get my electric motor to kick in like it used to. I've read how "overfilling the oil" can decrease your mileage (which they did...) but this shouldnt affect the issue of using my electric motor (should it?). Is this anything anyone else has experiencing? Could the dealer have done a software thing to cause this? Or have the oil companies forced dealers to do this so my fuel efficiant wondercar is not so wonderful. (HA!) Any help on this issue is greatly appreciated. I plan on calling the dealer tomorrow morning to see if they've heard of this issue before. I will update as I find out. Thanks!
How much did they overfill it? If it's just a little over it shouldn't have any effect on mpg's. You can take the airfilter out and hold the butterfly open and see if there's any oil pooling at the bottom of the intake manifold. More likely they lowered the sir pressure in the tires. Check the tires and make sure their inflated to 42 front, 40 rear. While you got the air filter out make sure it's not dirty.
Welcome to the cold season. No matter what you do to optimize oil, you simply can't escape the winter. The return of warmth is marked by a rise in MPG.
Yeah John your right about that. We've been lucky here in Poconos so far, but I forgot I think the midwest has been colder than us here.
<div class='quotetop'>QUOTE(galaxee @ Oct 26 2007, 10:43 PM) [snapback]531001[/snapback]</div> Great catch! I totally forgot about the hit you take from first-time tire rotation... it's been awhile.
Maybe when they checked the tire pressure they set it lower than you previously had it. Or if your MPG is gradually decreasing, maybe you have a slow leak. Either way, check your tire pressure...
Thanks all for the info. They oil was overfilled a little bit. Not a drastic amount. I checked the air filter and it was fine. I don't use the electric motor alone a lot, only when I go through town at 35. Never for more than 2-3 miles at a time. However that 2-3 miles of "99.9 MPG" really helped my mileage. The report I got from the dealer after the oil change stated they only changed the oil and refilled the washer fluid. There was no mention about the tires. So I don't know if that is an issue at this moment. Would any of that make it more difficult to use the electric motor? Thanks again for all the info/help.
Then it's merely the colder weather. Nothing to worry about (and there's nothing to be done about it, either).
<div class='quotetop'>QUOTE(nds @ Oct 26 2007, 02:48 PM) [snapback]530913[/snapback]</div> Hmm, I don't have the car here to check the manual atm, but in going through my 2008 manual I think I saw something about a condition where the ICE continues to run all the time that's caused by something getting lost/reset/etc. when the 12V battery is disconnected (the advice was to contact the dealer in this situation and have them reset whatever it is). So, if during service they disconnected the battery for some reason then perhaps this is a possibility. I'll see if I can find the exact bit in the manual that I think I'm remembering. Z.
