Can UOA disprove oil change claim

Discussion in 'Newbie Forum' started by BK2016eco2, Sep 22, 2025 at 8:38 PM.

  1. BK2016eco2

    BK2016eco2 Junior Member

    Joined:
    Mar 16, 2024
    13
    6
    0
    Location:
    Iowa
    Vehicle:
    2017 Prius
    Model:
    Four Touring
    Hi guys - I wasn’t quite sure where to post this, so I figured the newbie forum would be the safest bet.

    I just finished working on a very good friend’s car who has a receipt from a shop showing he was charged for an oil change that occurred less than 1000 miles and 6 months ago.
    From the look and feel of his oil, which I just changed for him (Valvoline R&P 5W-30). I can guarantee you this shop did not change the oil or the filter. The oil was black as I’ve ever seen any oil, was thinner than 0W-8, and the filter had numerous visible particulates in nearly every pleat. The car manual calls for 5W-30 btw - and the difference between what came out and what went in was noticeable to say the least. Also notable is the fact that the oil filter was a cartridge style, the cap for which had been torqued down to such an extent that my impact driver, which is capable of 140 lb.ft of loosening torque, had zero effect loosening the housing cap.
    I’ve kept the oil and the filter, but I have no idea how one would go about proving whether or not a shop had done the work that they said they did in this situation. The only thing I can think of is a used oil analysis - would it be possible for Blackstone or SPEEDiagnostics or any other company in the UOA space to disprove this shop’s claim to have changed the oil?
    I understand that definitive answers are probably not realistic, but any input is always appreciated.

    -BK
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    113,184
    51,518
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i think it would all be more trouble that it's worth. best thing is a bad yelp review, or threaten them with one and ask for whatever it is that will make it right.
     
  3. Mendel Leisk

    Mendel Leisk MMX GEN III

    Joined:
    Oct 17, 2010
    59,550
    40,964
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Oil can get quite dark, quite fast. Just to be on safe side, another oil change doesn’t hurt, and just move on. It’d be really tough to prove anything conclusive, and the onus is on you to provide the proof.

    I wouldn’t give them any “bad press”, it’s possible they did what they claimed. It’s also possible they didn’t, but do you want to smear a business when it’s not for sure?

    what’s the car in question, btw? A Prius of some ilk?
     
    #3 Mendel Leisk, Sep 22, 2025 at 9:53 PM
    Last edited: Sep 22, 2025 at 10:04 PM
    PrimeDan likes this.
  4. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    12,331
    5,007
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    This is a common problem with the disaster design of the Gen3 cartridge style oil filter. They didn't think through the fact that universal kits that oil change shops use for these cartridge filters looks like something you'd want to attach to an air power impact driver. And no big deal doing that taking it off. But it has created misery for so many of us who have to take one off if the minimum wage worker used an impact driver to put it back on. I highly recommend everyone replace that oil filter mount with one that accepts the exact same screw on oil filter used in Gen1, Gen2, and Gen4 Prius. And I hope Gen5 uses the same oil filter!
     
    #4 PriusCamper, Sep 22, 2025 at 11:21 PM
    Last edited: Sep 22, 2025 at 11:48 PM
    PrimeDan likes this.
  5. BK2016eco2

    BK2016eco2 Junior Member

    Joined:
    Mar 16, 2024
    13
    6
    0
    Location:
    Iowa
    Vehicle:
    2017 Prius
    Model:
    Four Touring
    Bisco - as a business owner, I generally don’t put out bad reviews about other businesses without first addressing the issue with them - They can’t fix what they don’t know is broken -
    I always approach them respectfully - without asking anything to “make it right”, and wait to see if they’ll see the opportunity to turn a negative experience into one I can promote with positive word of mouth. Every business owner I’ve done this with are thankful when they don’t feel attacked, and has never led to an escalation where I’ve felt it necessary to inform other consumers of the business as a bad faith actor.

    That said - the notion of this oil change having been done is one which I absolutely cannot imagine to be true. The vehicle is a 2nd one kept as a cheap insurance policy in the event something should go wrong with his primary transportation, and I wholeheartedly believe the owner’s claim that it hasn’t seen more than 1000 miles since the “oil change” occurred. I called the shop personally to confirm the receipt’s information to be true - I wanted to hear it from the horse’s mouth - and did.

    However - a “he said, she said” situation isn’t one worth slinging accusations over, as Mendel has rightly pointed out. But - if it were possible to get irrefutable data confirming my position - I would absolutely pursue that endeavor to bring it to the attention of the owner. Out of principle - I will never condone this type of shady practice from someone professing to be a mechanic - inherently deserving of trust in ways that can have catastrophic consequences when that trust is violated. An $80 UOA is well worth it to me if it allows me to call out that violation with irrefutable data provided by an impartial third party. I will take this route 100% of the time - not to get litigious about it, but out of principle.

    Mendel - the vehicle in question is a 2010 Chevy Equinox. It isn’t remarkable in any way - there’s no fiscal justification for my blood to boil, but I’m not going to pretend that it isn’t. The man lied to me, he’ll have a chance to acknowledge that mistake when confronted with evidence (if said evidence is possible to obtain), and it’ll be up to him how the situation unfolds after that.
     
    Mendel Leisk likes this.
  6. BK2016eco2

    BK2016eco2 Junior Member

    Joined:
    Mar 16, 2024
    13
    6
    0
    Location:
    Iowa
    Vehicle:
    2017 Prius
    Model:
    Four Touring
    Also - I should have mentioned that a UOA is primarily being pursued out of a need to make informed decisions going forward. If it returned information pointjng towards an imminent catastrophy, it wouldn’t make sense to replace the front brakes, calipers, or rotors (hypothetically). If the oil was just blackened due to some series of events that I didn’t know could lead to that result (to be fair - is a possibility) than I learned something. Or, If the cause of the oil’s condition was harmless and inconsequential - than maybe I advise that the additional investment to fix the brakes is fiscally sound.
    It’s more about informed decisions at this point - but I’m also hoping it’ll be a weapon allowing me to confront the issue.
    Without any sort of evidence that substantiates my claim, I don’t get to address it… and I suppose this post is me attempting to manage my expectations.
     
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    8,002
    7,476
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    UOA can tell you if the additives in the oil have been depleted- they'd report the TBN counts that help keep the pH from going too low with time and fuel combustion exposure.

    Thing is, it's not irrefutable, not by a long shot. You'd pretty much have to run more of the same oil through the same engine and get more analyses done at diffrent points in time to have some data to compare against the sample you have now.

    It could be informative. It won't be positively conclusive. It will take a lot of time and at least some money. Is that really worth it in the context of where to get future oil changes for a 15 year old Chevy?
     
    #7 Leadfoot J. McCoalroller, Sep 23, 2025 at 1:36 AM
    Last edited: Sep 23, 2025 at 9:42 AM
  8. Kramah313

    Kramah313 Active Member

    Joined:
    Oct 3, 2015
    411
    326
    0
    Location:
    Dallas, TX
    Vehicle:
    2012 Prius
    Model:
    Four
    Honestly I’d just have them take it somewhere else for the next one or DIY and compare how it looks after 1,000 miles. The odds of getting 2 different places to not do it and say they did in a row are astronomical IMO. If it looks the same this next time, it’s just how the car is. If it’s a lot cleaner, then you don’t ever go back to that shop again.
     
  9. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    3,119
    1,656
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    It's been 6 months and 1K miles; that's going to be difficult to prove - considering mechanic could've used thinner winter oil.
    Go someplace else and check their work next time. It's not that difficult to pull the dip stick and check oil. The time to complain is when your leaving the shop or next day at the latest.
    FWIW, those newer 4-banger GM engines does NOT handle missed oil changes very well......
     
  10. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    113,184
    51,518
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    how do you prove the used oil came from that car?
     
    PriusCamper likes this.
  11. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    12,331
    5,007
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Not sure why this is still worth discussing? If you have a problem with a sketchy oil change place and you don't bring it to their attention right away then it's no longer the oil change place's problem.