Burning oil affects gas mileage?

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.

 

Tire replacement. Eureka. Rath's found the root cause! That was easy.

 

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.

 

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