1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Seafoam/oil treatment or not?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by LuvLispy, Apr 19, 2024.

  1. LuvLispy

    LuvLispy New Member

    Joined:
    Apr 2, 2024
    7
    1
    0
    Location:
    Jonesboro, AR
    Vehicle:
    2010 Prius
    Model:
    II
    Well, the cars I used to have were FWD GMs with 3800s, those cars never really cared what you did to them as long there was oil in them. I ran STP and seafoam in those cars and they lasted me a long time with hard work.
    Not sure about the Prius though. Mine has 180k miles and I scheduled an EGR cleaning and spark plug change next week. But I wanna know if seafoam/stp in crankcase helps the car? Since these had VVT-i, I don't wanna mess things up. Car currently gets 47.8 MPG combined with some Lyft work, and I feel that the engine is still ok.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,814
    38,318
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Who's doing the EGR cleaning, what sort of place? How much?

    180K is very late in the day for this, btw. Don't assume a belated cleaning will turn back the clock; cylinder one and two have likely been running hotter for the last 50K.

    Plug replacement now for any particular reason?

    How long have you had it btw?
     
    Grit likes this.
  3. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,814
    38,318
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Grit likes this.
  4. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    5,928
    3,180
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    I have used 4ounces of seafoam the last 4 oil changes. I used the new Valvoline "Restore" last
    oil change a few weeks ago, and changed to the 2nd one yesterday.
    I turned 335,000 miles this week.
    I usually drive 63-65mpg and used about a quart every 2500 miles. I've been driving 65-67mpg
    and used 1 quart in the same miles. In the past I would use 2 quarts.
    so it "seems" that it has done something for the good.
    I figured with other 300,000 miles, it couldn't hurt it much. If it keeps the engine going for longer,
    I'm happy!

     
    MikeDee and Grit like this.
  5. HKz

    HKz Junior Member

    Joined:
    Nov 19, 2020
    20
    4
    0
    Location:
    Mesa, AZ
    Vehicle:
    2011 Prius
    Model:
    Two
    So I haven't lurked around on this forum to know all the common problems with the 3rd gen but obviously seen enough posts about the EGR valve and some head gasket concerns. We are gonna be nearing 200 k with our 2011 Prius, engine still run great, decent power, good MPGs...we never got either done. What do you think likelihood is that she's still totally healthy and is it worth doing an egr cleaning at this point?
     
  6. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    5,928
    3,180
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    It's a good idea to clean the egr system, which includes the intake manifold.
    It's preventive maintainence. Like changing engine oil.
    Keep an eye on the engine coolant. See where it's at when the car is parked
    overnight, and checked it once a week or so. If it starts going down, check for
    leaks, but if you get a knocking noise when the engine starts sometimes, it's
    likely a leaking head gasket. DO NOT PUT ANY SEALER IN THE COOLANT!!!

    Then replace the head gasket, or have someone do it for you. The sooner you
    replace it, the less likely you'll have a warped head, or throw a rod through the block.

    From reading on Prius Chat, it seems the ones that do mostly highway driving go
    the longest, city driving go less mileage.

    If you can replace it yourself, you could always change it before it fails, then you won't
    have to worry about it.
     
    HKz and Grit like this.
  7. HKz

    HKz Junior Member

    Joined:
    Nov 19, 2020
    20
    4
    0
    Location:
    Mesa, AZ
    Vehicle:
    2011 Prius
    Model:
    Two
    We have zero coolant issues so I'm not worried about the head gasket for now but alright I will take out the intake + egr and see what we got. We have had about 50/50 with our highway/city driving for its life, average about 48 mpgs (way better than my 22 mpg for the GR Corolla lol)
     
    ASRDogman likes this.
  8. MikeDee

    MikeDee Senior Member

    Joined:
    May 9, 2013
    1,536
    583
    0
    Location:
    San Francisco Bay Area
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    When was the coolant replaced? Water pump? Overheating kills the head gasket in these engines.