Excessive Blow by 06 Prius

Hey guys;

I wanted to bring this up, i noticed a drop in mileage on my prius that caused concern. It went from 49 mpg to 44 one tank to the next on a long drive. I noticed oil was below the lowest point on the dipstick. But the engine was warm at the time, i noticed it misreads when its warm.

Regardless i was due for a oil change, changed the oil, and am back to 48 mpg on my last tank, but i noticed that i also have a lot of blow by with the engine on and oil cap off.

I am burning oil, cant say how much, maybe 2 quarts every 5k.

I recently rebuilt the battery and dont want the motor crapping out on me after an expensive rebuild. I was wondering what you guys think i should do from here. Leakdown test to see if i have a leaky valve stem? I also read people mentioning that the piston rings can get stuck and it would be a good idea to add some detergent directly to cylinder overnight. I plan on doing the pcv soon, but its going to wait till the weekend. There is no oil in my airbox though, so im pretty sure the pcv is okay.

As for the blow by it feels like a hair dryer on medium, not scientific but its fairly strong. Advice much appreciated.

 

Sorry should have mentioned this earlier. It has an odometer change, but based on carfax, i can assume its around 225,000 mi. Currently using 5w30, before i would use 0w20, and synthetic since ive owned it. I owned it for 25k 1.2 years.

I havent looked inside the intake manifold, i looked at the airbox. The throttle body looked to be dirty, but normal, not wet and oily.

The blow by was measured after a lengthy drive, the car was fully warmed up.

I understand that it might not be too bad to have that much oil consumption at my mileage, and i still get good mpg. But I should be getting 50 easy, if not better, i used to. Also I don't like the fact that i am polluting excessively. If it is a relatively easy fix such as detergent in cylinder or pcv i would like to do it. If i need to change valve seals, it doesnt seem like it would be too hard. I almost finished swapping a head on my cherokee, and recently rebuilt the hv battery so I am mechanically inclined. I just wanted some feedback.

We have one other prius that exhibits this much blow by, i dont think this is normal but can anyone else check and report back?

Thanks again you guys are being super helpful

 

Thanks for that, you are so right.

im starting to think that i might benefit from adding a detergent to pistons. Anyone have experience with a certain product, or procedure. Does the detergent leak into engine oil, since i just did an oil change i wouldn't want to do another one.

Thanks a lot, never knew that. I will try that out this weekend. It seems strange that that much crankcase pressure would be normal under any circumstances though. Im surprised this hasn't been discussed yet.

First thanks for chiming in , and i did see your first post where you mentioned you experienced this. I know that no one has talked about this being valid on prius, but i think the prius engine is more similar to a standard engine that one might think. I could be wrong but at this point I am just trying to troubleshoot.

I sure hope so, with the money dump that is the hv i was hoping to stick with this thing for a few years .

This whole issue came up because of a drop in mpg, which has gotten better since the oil change and tire inflation. I guess my mileage could be worse do to abnormally cold weather in so-cal. I guess im just used to seeing very consistent numbers and when things went awry I panicked.

Still, I am thinking of doing a compression test, if i do i will report back.

Y'all are awesome

 

Pattern has been 49 avg

recently started driving to san diego, first few times it was right around 49. All of a sudden it dropped to 45, i just filled up and mfd lied and i calculated 45 again. right now mfd is saying i got 43mpg over 100 mi so i dont know what to think. If i have a chance i will fill up tomorrow and report back. but such a drastic drop in mpg is strange. The differences are, tire rotation done before drop. tires inflated warm at 44 warm in front 42 warm in back, oil was dangerously low so i changed it and instead of 0w20 mobile 1 i went with 5-30 penzoil platinum.

 

5% would only be 2.5 mpg. im getting 10% reduction. i might just do an oil change on it again and put that oil in my jeep if you guys feel that it makes that much of a difference.

I know that we there is a change with winter gas, but nothing i havent already experienced. unless this year the gas is diff? Also since my avg of 49 is with ca gas i think its only fair to keep comparing my mpg drop to same gas. But its good to know that other locations offer higher energy gasoline

Starting to eye some used prii on cragslist , i dont want to spend money. Btw 2016 prius is fugly, i would rather not go there lol.