I'm burning about 1 qt of oil per 5000 miles in my 2006 with 90k miles. None of my previous six vehicles burned oil (the Vanagon doesn't count--it's supposed to burn oil just like all 1980s VW vehicles, right?). This is a major disappointment and I'm questioning toyota's reliability credentials in consideration of other troubles I've had with the car. Yes i know its not a lot of oil and well within spec. Anyway here is a question for the mechanics in the audience, is it possible to observe reduced mileage (about 4 mpg in my case) as a result of the oil burning problem? In advance thanks for your insights and please don't respond if you don't understand how an engine works.
One of the things that oil burning can be caused by is a poor seal between the piston rings and cylinder wall. The resulting loss of compression into the crankcase can result in reduced power and fuel mileage. However, in your case, the amount of oil consumption you are experiencing is more or less normal. In fact, in years past it would be considered really good. There is nothing about the consumption of that amount of oil per se that would cause a MPG drop. As to your drop in fuel mileage, the first questions I'd ask is how old is your 12v battery and what are your tire pressures? With more info as to what has been done to the car and any other symptoms you may have, I or someone else may be able to help.
No doubt the car is very sensitive to a number of elements that contribute to fuel economy. Added weight, tire composition and air pressure, wind direction, 12V battery health, HV battery health, engine health, the health of all friction surfaces, and motor oil weight. My 05 burns 1qt per 5k. I am presently running 0w30 synthetic. I will be changing soon to 5w30 synthetic. I expect to lower oil consumption a bit but may also see a slight hit in mpg. I presently average around 50mpg in combination city/highway use, though we can get around 60 when feeling especially conservative driving in the country. But I am not particularly bothered either by the mpg or the oil consumption. It does seem like the factors that most commonly effect mpg in the Prius are tires and battery health. A 4 mpg hit could be caused by either of these.
Note that Rath doesn't mention what the mpg currently is and what the other "troubles" are that they've had with their Prius. And their first post to boot. 1 qt oil/5K miles is a major disappointment? No way, Jose. 1 qt oil/500 miles is. 1 qt oil/5k miles will not cause a 4 mpg decrease. Look elsewhere for the root cause, Rath. You're stone cold right now.
Sounds reasonable. What type and grade oil are you using? Unlikely at the levels you're encountering. You could try changing your sparkplugs and see if that helps.
That's helpful info Joe about the relationship between oil burning and a loss of power. I hadn't thought of it that way. I also appreciate your interest in trying to help me resolve the mpg shortfall. I didn't elaborate because i believe I have explored most of the obvious and not so obvious reasons for the drop (thanks Priuschat!) But since you asked, I replaced the 12v battery last year, am religious about tire pressure, air filter replacement, and other upkeep, and didn't change how or where I drive. The drop seemed to roughly coincide with the installation of Michelin Energy Saver tires last year and winter. Winter is gone, which obviously affects mpg, but not the poor mpg. I'll keep searching.
The fact that you're burning the same amount of oil as my Prius indicates that Joe26 is right. See my response to Joe26for more detail. Your post really helped me evaluate my problem. Thank you.
Thanks uart. I'll give the spark plug change a go. I'm using the oil recommended for the vehicle per the owners manual. Can't recall the weight exactly.
Not sure why you're compelled to join the discussion since this was already addressed in the first post.
Because you clearly have no idea what caused the mpg drop and no clue of how to find it. Replacing worn out tires with new ones usually results in a temporary decrease in mpg. Sorry to be helpful.
Youre right new tires can impact mpg for the worst. However mine have over 5000 miles on them. I respectfully disagree that my mileage drop is a result of the tires given their wear.
Finally more details emerge. That's what we've been waiting for. I would hope that the Michelin energy savers have minimal wear after 5000 miles. Which would still make them nearly showroom new. What mpg were you getting before the precipitous 4 mpg drop?
Ralh, I would simply like to ask these questions. What are your air pressures now on your tires? I understand you are "religious" about tire pressure. Also, for the record what is the size of the tires you are running now? What brand and series of tire did you replace when you switched over to the Michelin Energy Saver? Also did you change sizes of tires when you replaced the old ones? Finally, what is your average MPG now? Ron
I wanted to close the loop by sharing the resolution to my issue. I brought the vehicle into the shop and the only thing they did that would impact gas mileage was cleared the 15 engine error codes. Voila. My gas mileage improved. They suspect the error codes were a result of the auxiliary battery woes I experienced before replacement. Interestingly, it may be that my gas mileage was fine, but the car's internal capability to read mileage was impaired in some manner by the error codes. I didn't manually check gas mileage while having the problem of reduced mpg, so I can't verify. Since the fix, my mpg has improved by 2 to 3 mpg over normal (not the artificially low numbers I was getting recently) which I attribute to the Michelin Energy Savers that I installed immediately after I experienced the mpg drop. Now, around town, I'm getting about 50 mpgs!
