Poor Mileage Since Oil Change

[2009Prius]

Unless you have a plug-in, all power comes from the engine and the net contribution from the battery is less than zero because of conversion loss. I would think the battery would be good enough to do its job until it fails unless you drive in very hilly area or have frequent stop and gos. I guess the conversion loss may increase slightly overtime.

[richard schumacher]

Originally Posted by cfvettes

I called the place that did the oil change and they said because our car was an older Gen II and because we had 80K miles, no doubt our hybrid batteries were wearing down, getting weaker and unable to deliver power like they used to. He said in this case more power comes from the engine with less contribution from the hybrid motor. Leading to a decrease in mileage.

Could this be true? And how do you know when its time to change the hybrid battery?

That much battery aging does not happen in the course of one tankful! They're blowing smoke at you, hoping you'll go away. If any of the battery modules fail you'll get warning messages.

The consistent picture we get is that the quicky lube places provide less reliable service than do dealers.

This MPG change is almost certainly caused by tire pressure. If they reduced pressures to 32 PSI when the tires were warm then that left the pressures much too low. Pressures should always be measured with tires "cold" meaning driven no more than a mile in the previous hour. Inflate the tires properly, drive for a while and see what happens.

[jayman]

Originally Posted by cfvettes

I called the place that did the oil change and they said because our car was an older Gen II and because we had 80K miles, no doubt our hybrid batteries were wearing down, getting weaker and unable to deliver power like they used to.

Bull

and

S***

Who knows what kind of oil they had sitting out in the bulk tank out back? 10W-40? 20W-50?

Set the tire pressures properly. If you are unwilling or unable to change your own oil, find a place that you can trust.

[FrankD]

Thank you again Priuschat for again being smarter then the dealership, etc....
I do not want to hijack a thread, but I was just reading this thread, and I too have been a tad disappointed with my new to me Prius MPG. I'm still a newbie, and bought a 2007 Pkg#3. I've driven it now less then 1k, and I know that the dealer changed the oil just before I bought it.

I just checked the oil for the first time, and it is a solid 1/4" ABOVE the full line with a cold engine. That should explain the lower MPG's....(avg MPG for is 40-45)

I did change the almost new Michelin Harmony tires to 42/40. They had it at 32psi. I trusted the dealership because they told me that they work on "a lot" of Prius's even from other dealerships. I did have my doubts about them when a week after I bought this "Toyota Certified" Prius, I found a plug in the tire, right on the edge of the sidewall on the flexpoint, which is dangerous. They told me they did not do it and did not know how they missed it. I then looked at the carfax report they gave me and it showed that THEY repaired the tire less then a month before! I made them order a new matching tire and they replaced it at no charge.

Is there a book I could buy that shows step by step maintenance for the Prius....like a Chilton's manual or something? I have not been able to find one. I'm no mechanic, but I usually do my own simple maintenance on my rides.

Is it harmful to my car to have been driving it 1/4" above the line? Or does that just hurt the MPG's....?

Thank you in advance for your kind "newbie" help.

Frank D.

[jayman]

As far as books to buy, I've heard good things about the Bentley repair manual, have never used one. I have a subscription through All Data DIY that has the same information as the factory shop manual

One of our forum members, John1701a, has put together very informative DIY procedures for things like oil changes and cabin filter changes.

John's Stuff - Toyota Prius Maintenance - Changing Oil

Our mad scientist forum member, Hobbit, has information on everything from cleaning the rear parking brake, to changing the cvt fluid.

Hobbit's techie-rants

Hope this helps

[ETP]

Originally Posted by yardman 49

So this brings up another question for me: why trust the dipstick?

I just had the first oil change done on my 2009. I told the Toyota dealer's shop that I didn't want it overfilled. In response the service writer told me that they had to put in the recommended amount.

When they finished, he gave me me a printout from Toyota that clearly states that an oil and filter change should take 3.9 quarts of oil. When I checked it when I got home, the dipsticked showed about 1/4 to 3/8 inch over the full mark.

So should I leave it as is, or drain some out. And if I should take some out, can I use one of those oil suction pumps to pull it out through the dipstick tube?

Thanks

I never trust the dipstick but use it as another data point. The only way for sure is to do you own oil change and measure the oil to the full mark on a flat surface after the car has set for an hour. 1/4 inch I would not freak out over. Two inches yes! LOL

[FrankD]

Thank you Jayman!

Frank D.

[jayman]

Best of luck. First time taking the filter off, it's a bit of a blind reach. Once you get used to it, no problems. I never used ramps to change the oil in my Prius, but did use a very shallow pan to collect the oil

I first took a metal generic drain pan, cut it down to fit under the car. After all that donkey work, found at Wally some Tupperware containers that would have worked perfectly

[E Todd]

I've found that by using a simple utility light and correctly placing a small mirror under the car I can visually see well enough to install the new oil filter without any ramps or jacks. I don't know why I didn't think of this before. I changed the oil in my wife's '02 Camry yesterday and it worked well on that car too. Geez, I love these Toyotas!!!

[PearlDriver]

I always tell the techs not to overfill. It's amazing how many want to argue. "The book says..." Then I show them that the book also describes the operating range. I make them adjust it so they will remember next time.

Tire pressure and defog are the two that have hit me in the past.