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Do I believe the evidence or the dealer?

Discussion in 'Gen 2 Prius Fuel Economy' started by dulecki, Dec 17, 2007.

  1. dulecki

    dulecki New Member

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    I've got a 2007 Prius, basic edition. When I got it last year, I experienced unacceptable mileage, found this site, changed my habits, and graduated to 45-48MPG, depending. Since I work out of the house and many of my commutes are 5 minutes or thereabouts, I don't feel too bad about that.

    I've been driving that way for the last nine months. At least, up until the second oil change.

    Immediately after the oil change, my mileage dropped to the mid to upper 30s. Since I'd just gassed up as well, I thought bad gas... but five tanks later, I've ruled that out. I went back to the dealer to check it out, and they said no readings were abnormal, and proceeded to explain how to drive a Prius. Apparently the fact that I'd been doing that for the past year didn't count for much.

    I came back here and learned about blocking the grill, which I've done. MPG has increased about 2-4 MPG, but still well below what I used to get. I'd love to break 40 again... I think that sums up my exasperation.

    Since the oil change, the weather has ranged from sunny and warm all the way down to frigid cold (10s and 20s). Mileage has not varied with the change in temperatures.

    So... what I've done is:

    • Doublecheck the tire pressure after the dealer visit and found them in the mid 30s, which has been corrected.
    • Check the oil levels (appear to be normal/not overfilled)
    • Block the grill
    • Change gas stations
    • Pay extra attention to my driving habits
    • Minimize use of the heater
    And no success.

    Aside from the rookie discussions when I took the car in to get it checked, I have been frustrated that my dealer keeps slapping up 3000 mile oil change stickers. I've changed at 5000 per the manual, not doing anything extra special with the oil.

    I'm concerned about my dealership's ability to service a Prius. I don't know if that's well-founded or not, but it's happening.

    So my question, at the bottom of all this... what else can I do? I'm very tempted to go someplace else to get an oil change done and see if that has as dramatic an impact in the other direction. I'm only 2500 miles into this oil change, but this is getting ridiculous.

    Any thoughts and ideas will be greatly appreciated.

    Thanks!
     
  2. a priori

    a priori Canonus Curiosus

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    If there is an award to be given for top first posts, this one has got to be in the running.

    Congratulations on making such an effort to educate yourself, identify issues, take action, etc. Clearly, you've been able to make the changes that should make a difference. One thing that you cannot change, though, is likely going to make your "low" numbers stick: You only drive in 5-minute intervals. In the winter, this really shows up as a "problem" for those striving to increase MPGs.

    One thing you can change is your dealer. Either go to another dealer or take the time to educate the dealer. You are not going to be able to increase the mechanics' abilities or knowledge of automobiles (unless you are a mechanic yourself), but you will be able to educate the dealer about YOUR INTEREST in having the Prius achieve its maximum potential.

    I have been wondering myself why I've experienced a noticeable drop in MPG since my first (5,000 mile) oil change. I've put on about 1,000 miles since then, and I still see this decrease. Some is likely weather related, but could all of it be from the cold? I increased the tire pressure the afternoon after the oil change (the dealer had dropped it, but only to about 40/38). I had blocked the grill prior to the oil change (and since increased it to a full block). I turn the heat on low only after the first five minutes (if at all). And I wonder what happened at the dealer's garage.

    I am thinking (and hoping) that it really is just due to the very cold weather. Just yesterday I had two 55-minute drives, mainly expressway. Normally, I would have seen MPGs in the upper 50s. Instead -- outbound was in the low 50s and the return was in the upper 40s. I think the cold and, the sloppy roads combined to drop the mileage. Just as I've noticed lower MPGs in rainy conditions, I think MPGs drop when I drive on sloppy roads during and after snow storms.

    Like you, though, I'd be interested in some other views about what could be done.

    Yes, the EBH is on order and will be arriving soon!
     
  3. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I agree with apriori. That's a good post and you are clearly working to improve your car and mileage. Congrats.

    Please review my mileage chart in my signature. One thing you will notice is that when the mileage starts going down, it drops like a rock. A big rock. But notice that my first winter was the worst but then things got better as I became a better driver and the car broke in.

    And a priori is correct on a couple other aspects as well. Sloppy roads are horrible, just horrible, on mileage. The cold is a major factor. And even though my tires say they are fully inflated, I swear my stealthing/gliding distances are considerably shorter in the cold.

    So in the end, it might just be that it's the first winter and you're going to have to stick it out like the rest of us.
     
  4. kettledrum

    kettledrum Member

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    Ah ha. Maybe I'm not crazy. Even when the roads were perfect, but it was just colder out I had been noticeing shorter gliding distances. I too had checked my tire inflation, but that wasn't the culprit.

    To address the OP, I would guess that you *might* not be able to make any definite determinations until next spring when temps have moderated to what they were when you were getting 45-48 mpg.
     
  5. dulecki

    dulecki New Member

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    Thanks for the feedback, folks. A couple of additional notes in here...

    First, I've had my Prius since November last year. I've already gone through a winter, and gotten mileage in the 44-48 range. So this drop in mileage, at least in my mind, is not related to winter or driving habits.

    Second, it started in September, long before winter kicked in. Since then, it's been warm and cold, the roads have been great and crappy, and the mileage has sucked either way.

    Basically, on a Thursday in September, my mileage was around 45. After the oil change on Friday, it was around 35. That fast... like flipping a switch.

    The only variables that changed (that I know of) were the oil change (and whatever else they might have done) and the tank of gas. I've never experienced a mileage drop from any other tank of gas, and I'm not one who insists on a particular brand of gasoline. So the odds of getting something a little different in the gas tank over the past 12,000 miles are pretty good.

    I'm not ruling me out as a contributing factor... but AFAICT, "me" is pretty much a constant in this mix.
     
  6. a priori

    a priori Canonus Curiosus

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    I apologize for the assumption I made about being a new Prius owner/driver.

    You've now taken an interesting post and made a real mystery of it!
     
  7. dulecki

    dulecki New Member

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    No worries :) I wasn't specific enough in my first post, so it was an easy assumption to make.

    I actually held off making the first post until I'd had a couple hundred miles driving with the blocked grill, just so I'd have some details to support what I'm experiencing. Yes, I'm obsessive... and now, a little perturbed that I didn't keep detailed notes on my mileage like Tony... next time...

    It does feel a bit strange, I have to admit, complaining about getting 36-37MPG. In my previous vehicle, I would have been ecstatic. In our minivan, I'd be so excited there'd be little puddles behind me.. ;)

    *edit*
    I should say... my next step, unless someone has a better idea, is to get the oil changed somewhere else (either another dealership or an oil change place... haven't decided) to see what impact that has. I'm looking for ideas on that.
     
  8. a priori

    a priori Canonus Curiosus

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    Thank you for a gracious reply.

    You've probably read through the numerous posts regarding oil changes on PC. Many people have written to complain and warn against going to quick-change shops. Many others have complained about dealerships, but feel their warranties are not in trouble if they go to Toyota dealers for service. A very vocal group says: "Change the oil yourself -- it is easy and cheap!" There is a rather recent thread showing you just how to do this easy task.
    I used to do all the maintenance on my cars. I also used to get very cold and dirty doing it all outside. Now I wait in the heated room at the dealership and try not to think about it too hard.
     
  9. apriusfan

    apriusfan New Member

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    You might try that to rule out problems with the oil the present dealer is using.

    If you do switch where you go to have the oil changed, you might want to consider synthetic oil such as Mobil 1. Also, a block heater could be something to consider, even though your mileage last year was not as bad as this year. Lastly, did your area recently switch to ethanol additive in the gas?
     
  10. inventor00

    inventor00 Active Member

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    Did the dealer do any software upgrades that they forgot to tell you about? I noticed in the '04 that when they re-programmed the computer, we got much worse mileage.....
     
  11. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    If they put the wrong oil in, that would explain everything. A higher viscosity oil would really be noticable in the MPGs.

    If that happened to me, I would either have the oil sampled or ensure that I got it changed with oil I bought. You have eliminated just about every other factor that would cause that big of a change, other than a computer update...and that should not cause it to drop that much.
     
  12. a priori

    a priori Canonus Curiosus

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    I hadn't thought of this as a real issue. Would there be a noticeable change in MPGs if the oil was changed from 10W30 to 10W40?
     
  13. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    Having changed the oil on a 2001 Prius for 7 years, I noticed a ~1 MPG improvement with the new oil of the same viscosity. This required lots of oil changes and lots of data to verify since a 1 MPG change is so easily affected by many other factors. The Prius gets such high MPG that it is sensitive to everything (temp, oil, tire psi, etc)....and something really big had to change to cause that much drop.

    So, yes changing the viscosity does change the MPG. Now what would happen if they put in 20W-50? Big changes in MPG. Now I am guessing like everyone else, but you really have eliminated just about everything else.

    (Search for posts by jayman to get a firsthand description of a Toyota Dealer putting bad oil in a Prius.)
     
  14. patsparks

    patsparks An Aussie perspective

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    Welcome to PC.
    How is your parking brake? Did that get higher after the oil change too? It is possible the park brake is adjusted too tight causing friction in the rear brakes. Check for heat in the rear brakes after a drive, they should be reasonably cold with normal Prius driving.

    Hey wrong oil wont just reduce mileage but it can damage the engine. I have seen engine damage caused to an engine that should have had 10w-30 but 20w-50 was used. The 20w-50 oil is too thick for the fine clearances in a modern engine
     
  15. paprius4030

    paprius4030 My first Prius

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    The correct oil would be 5W-30. Don't forget to check the air filter
     
  16. kettledrum

    kettledrum Member

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    Thanks for the further explanation. Had no idea you had already been through a winter. Oops.

    At this point I would want to change variables one at a time. I might see what happens when the oil is changed again, but not make the switch from dino to synthetic as that's changing two variables at one time. You might not know which one of those made a difference if you suddenly get another change. But that's just me being methodical.


    What all in the engine needs to be checked if it was the wrong weight of oil? Or too much oil??
     
  17. dulecki

    dulecki New Member

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    Thanks, everyone. Made a roundtrip to Detroit today and for the first time since September, averaged over 40. Woohoo! I haven't made any changes yet, so that's just a result of slightly warmer temperatures and blocking the grill. I would have expected to see 48 before...

    Tomorrow, I'll be heading to another dealer to have the oil changed. I'm going to dig up the paperwork from the last oil change to see if they did any other work at that time, and I'm also going to read the postings here on oil change options. I'll hold off on synthetic until the next one... as was said, one variable at a time.

    More news when I get it...

    Thanks!
     
  18. JimN

    JimN Let the games begin!

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    I wouldn't think that changing the oil from 5W30 to 10W30 would cause a noticeable difference. I have a crankcase full of the heavier oil and mpg did not decrease.
     
  19. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    I should not because the running viscosity (30) is the same. The cold, starting viscosity (5W or 10W) determines how fast the engine gets lubricated on startup (I am sure you knew this already, so this really is not aimed at you).

    In the case of the OP, if the dealer put in the wrong oil, it could have been really wrong rather than just slightly different. It looks like the OP knows what he is doing so I expect we will find out before too long.
     
  20. galaxee

    galaxee mostly benevolent

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    standard dealership oil stock is
    0w20
    5w20
    5w30
    10w30

    make sure they put 5w30 in there, but concerns about extremely heavy stuff are probably not worth thinking about.

    you should get an itemized list to see if they did anything other than change oil and rotate tires.