I've got a 2010 toyota prius. I'm on a road trip and changed the oil right before I took off, unfortunately I was in a hurry and didn't realize I overfilled the oil. (likely 0.5-1.2quarts overfilled ) when I realized it was overfilled I did some Google searches and saw suggestions to siphon through the dip stick, unfortunately it was 4a.m. And the only open place was Walmart and they didn't have a pump with a narrow enough tube.

I did more research and found that it shouldn't cause a problem unless it starts frothing which it wasn't. Today I've taken turns with my wife and driven all day checking the dip stick religiously and haven't seen any frothing, we are getting slightly worse mileage than normal although I chalk that up to our trip raising in elevation (Texas to Utah)

Anyways, during this last check I saw slight frothing on the dip stick, I am 400 miles from my destination, at which point I can drain the excess oil, but am now worried that driving will damage my car, is it likely I have already damaged it? Is there anything I can do in the middle of nowhere to help the problem and am I safe to drive? If I stay put for a while will the frothing go down? Thanks in advance for any help.

  • I went to a flying J and got tools to drain a little bit, now my question is did I likely do any kind term damage and is there anything I should watch for because of this?
    – Isak Jones
    Jun 13, 2017 at 5:28
  • most likely not - if it froths too much the pressure can increase and oil starts coming out everywhere - if it was not too bad then it may all have been absorbed by the crankcase ventilation system and fed into the engine induction air. Keep an eye for any leaks for the next few months.
    – Solar Mike
    Jun 13, 2017 at 7:09
  • 1
    If you're really worried about it and can't easily get the excess oil out yourself, stop somewhere and get an oil change.
    – 3Dave
    Jun 13, 2017 at 20:21
  • Any garage or oil change place should be able to do this for you in 5 minutes and for a very small fee. It's probably a better option than ending up with a bunch of oil in a drain pain in a walmart parking lot.
    – raydowe
    Jun 26, 2017 at 10:15
  • Thanks for the info, I ended up with a bunch of oil in a cup in a flying J parking lot. Everything seems to be going good since then except worse mileage, but I'm driving in the mountains of Utah as opposed to flat Texas which might be the cause of that.
    – Isak Jones
    Jun 27, 2017 at 2:09

1 Answer 1


Your car is likely to be fine if you drive it gently. But, I would drain some if you get a chance. Loosen the oil pan plug until you see a drip if you can manage and wait it out. Walmart has some cheap drain pans and I'm sure a pair of pliers.

I've done this with about 0.5 extra quarts and the gas mileage and power loss was noticable, but now I'm still driving it 7000 miles later with no threatening problems.

I had recently purchased the car, so take this with a grain of salt... I now burn a small amount of oil and it may have been caused by me accelerating hard with too much oil. I also didn't empty the oil out and let the extra burn off. Try to keep it under 3000 RPMs for the time being.

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