How long can one delay a synthetic oil change past 6 months?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by chinarut, Dec 30, 2020.

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  1. chinarut

    chinarut Junior Member

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    Not surprisingly due to the pandemic, I only drove 1169 miles in the past 6 months since my last oil change at 15k for my 2019 Prius LE back in June 2020.

    While I totally get Toyota's recommendation is to change the oil after 5k or 6 months, how wise it is to wait for another 6 months to change my oil? What kind of issues is one risking by waiting?

    The oil was changed at a Toyota dealership (synthetic) and the last 500 miles was all freeway so no stale gas in the engine or my tank.

    Thanks for any opinions.
     
  2. alanclarkeau

    alanclarkeau Senior Member

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    The safe answer is - go with TOYOTA's stipulation for any car under warranty. Not sure about how long there - but it's 7 years warranty here (on engine and drivetrain) - with it stipulated that servicing MUST be by the book.
     
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  3. Elektroingenieur

    Elektroingenieur Senior Member

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    That’s true (in the U.S., for model year 2019) only if you’re not using the recommended 0W-16 oil or if one of the specified “special operating conditions” applies. Otherwise, the Maintenance Log section of the Warranty & Maintenance Guide (PDF) says to replace the engine oil and oil filter at 10,000 miles (12 months), 20,000 miles (24 months), 30,000 miles (36 months), and so on.

    With this longer interval, it’s as important as ever to check the engine oil level at least once a month, as the Guide recommends on page 35. See the Owner’s Manual (PDF), page 609, for the procedure.
     
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  4. FuelMiser

    FuelMiser Senior Member

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    I'm too lazy to look it up right now, but isn't "frequent short trips" a special operating condition requiring the shorter change interval? The point being that short trips does not bring the oil temp to full operating level keeping harmful by-products from burning off.
     
  5. royrose

    royrose Senior Member

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    I would call 1,000 miles in 6 months "infrequent short trips". I wouldn't worry about it, wait for a convenient time that is safe as far as covid is concerned.
     
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  6. chinarut

    chinarut Junior Member

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    Thanks for all the responses and educating me on these matters Hope everyone is having a good start to 2021.

    To clarify:
    • The bulk of the 1169 miles that is highway driving is 583 mi in Sept 2020 (3 month mark) and 465 mi in Dec 2020 (6 month mark)
    • Three 25 mi roundtrip nature trips (~75 mi)
    • This leaves 46 mi for 2-5 mi bi-weekly grocery runs and random errands which sounds about right
    I reviewed the maintenance guide again and I guess with my erratic use of my car the last 1.5 years, it’s not clear if I’m “by the book” - I think I’ve been fairly aggressive changing my oil:
    1. purchase: 6/2019
    2. service: 04973 - 09/17/2019 (3 months) (4973 mi in 3 months)
    3. service: 12010 - 01/22/2020 (7 months) (7037 mi 4 months)
    4. service: 15248 - 07/13/2020 (12 months) (3238 mi 6 months)
    5. current: 16417 (01/6/2021) (19 months) (1169 mi in 7 months)
    “Technically” I’m due for the “20k (24 months)” service in 6/2021...
     
  7. sam spade 2

    sam spade 2 Senior Member

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    All of those details are pretty much irrelevant.
    The general rule is 12 months.
    And if it gets a good run once in a while, I wouldn't worry about going 6 months past that.
     
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  8. thomassster

    thomassster Member

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    Nothing wrong about oil change often except for money in your wallet. Toyota care for my 2019 maintenance is once a year every 10,000 miles, so you should be good.
     
  9. Ozark Man

    Ozark Man Member

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    I have a similar situation and I have been debating with myself If I should change mine at 6 months. I have about a month left and it is just changing to a dark golden color. The total mileage is 24,000 miles and the previous corporate leasor had changed it around 10 and 20 thousand even though he apparently didn't drive much either. I know some people say color has no meaning as far as wear is concerned. I usually drive about 20 miles round trip a week, but about 6 of that is at 65 MPH on the interstate. So this should get it up to full operating temp. And right now, usually about once a month I make an 80 mile round trip, most of it on interstate. The "care care nut" a Toyota technician on you tube says you should change it every 6 months or 5000 miles, no exception, if you want to get high miles from your vehicle which I do. It looks like I will only have about 2000 miles on it at 6 months. I need to save every penny I can but don't want it to cost me in the end. The "car care nut" seems to be totally on the owners side and know his stuff. He says Toyota is wrong to recommend the 10,000 mile yearly oil change and they won't be there to rebuild your engine when it starts to use oil prematurely. What does everyone think, 6 months or one year if only driving about 4 or 5 thousand a year.
     
    #9 Ozark Man, Aug 17, 2021
    Last edited: Aug 17, 2021
  10. sam spade 2

    sam spade 2 Senior Member

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    Self proclaimed experts who post things on the Internet often are NOT experts at all.

    But your answer depends in part on whether or not you KNOW that you have full synthetic in there now.
    If you do, then 12 Months or 8K miles is plenty often enough.

    Personally, I would not worry for one second about letting it go for 24 months as long as it is getting some regular use.

    And yes the color of oil in an engine means NOTHING.......unless maybe it is jet black and smells burnt.
     
  11. PtPri

    PtPri Junior Member

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    English mechanical lore says one should change every 6 months, but here in Portugal (much warmer and drier) that's seen as preposterous - one year is the rule.

    I don't know if severe temperature variation plays a role?
    Toyota mandates yearly service on my car.
     
  12. Ozark Man

    Ozark Man Member

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    Yes the records are on the Toyota website and the 2 changes so far are full synthetic. Thanks for your input.
     
  13. Elt31987

    Elt31987 Active Member

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    Blackstone labs claims to have tested oil with a few thousand miles on it that was in the vehicle for several years and showed no noticeable change in viscosity, additive package, moisture content etc. I guess modern engines are pretty well sealed and let little to no moisture into the engine which could extend oil life
     
  14. sam spade 2

    sam spade 2 Senior Member

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    I probably shouldn't say this but............
    Just because they wrote that on a service record, does not guarantee that is what they actually actually DID.
     
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  15. Colorado Boo

    Colorado Boo Member

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    My opinion is that once a year with those low miles should be fine. I would be more concerned with the health of the hybrid batteries...sitting unused for long periods isn't good. Try to get her out on the road for more trips....at least 50 miles. (2-3 times a month)
     
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  16. Ozark Man

    Ozark Man Member

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    This is
    This is true. Actually it showed 3 changes because the dealer I bought it from, certified, said they changed it also. If they put in the recommended 0W20, as I understand it only comes in full synthetic. Of course, I know there is no guarantee that they used that. But it's not something I'm going to worry about.
     
  17. Ozark Man

    Ozark Man Member

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    Well it's only sitting unused for a week at a time. Plus, my understanding is that the Li-On batteries are not as affected by not being driven as much because they do not self discharge to any degree as the Ni-Cad did. I know most people say they need to be driven a lot to maintain the battery's but I haven't seen any data to prove that as they are too new. Anyway I'm not planning on taking trips just for that reason. That sort of defeats the whole "saving money on gas" purpose. Hopefully I can let everyone know the battery is still good in about 10 years. Good advice, though.
     
    #17 Ozark Man, Aug 19, 2021
    Last edited: Aug 19, 2021
  18. Mendel Leisk

    Mendel Leisk Sand Pounder

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    And you shouldn’t worry; Toyota makes no stipulation that synth is required.

    I’m in the 6 months or 5k miles camp, fwiw.
     
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  19. sam spade 2

    sam spade 2 Senior Member

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    Yes they DO. Because they strongly recommend an oil that is not available EXCEPT in a synthetic.
     
  20. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Conflation.

    you should have a read through the Australian Owners Manual: the whole gamut of oil weights is “condoned”. The word “synthetic” appears maybe twice in OM, used to describe upholstery material IIRC.

    Normally I don’t see your contributions, but I though what the heck.
     
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