Do the pistons move when in EV mode?

Discussion in 'Prime Main Forum (2017-Current)' started by Worldbuyer, Aug 19, 2020.

  1. Worldbuyer

    Worldbuyer Junior Member

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    Sorry if this has been answered but I couldn't find a thread. Getting my oil changed and it occurred to me that I'm doing it based on mileage. Obviously the first 26+ miles of my daily journey is in EV mode, so I'm wondering how often I really need to change the oil. I can't seem to find an analysis of EV to combustion run time/mileage (that would be so cool). So I'm wondering since the drive train is moving, is the combustion engine moving while the car is moving? It would seem really inefficient but makes me wonder.
     
  2. bisco

    bisco cookie crumbler

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    not under a certain speed. 84mph? but it is a trick question, because there are certain instances where it will spin the engine. very unusual though.

    i change the oil once a year, rain or shine, but every other isn't out of the question, according to my mech.
     
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  3. schja01

    schja01 One of very few in Chicagoland

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    I thought the same thing. Service rep and some comments here say change annually as manual says if nothing more than to protect the warranty. Oil oxidizes sitting in the crank case I'm told. As to the pistons moving they will if you use B mode but no fuel is burnt. If it's below 17°F(?) or you run the defroster then the ICE will probably run and burn fuel.
     
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  4. john1701a

    john1701a Prius Guru

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    No, they do not.

    This video with the aftermarket gauge on the right show engine RPM as 0 the entire 30-mile drive.

     
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  5. jerrymildred

    jerrymildred Senior Member

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    Not on a Prime in EV mode. The pistons do not run until you come out of EV except sometimes in EVAuto.
     
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  6. Worldbuyer

    Worldbuyer Junior Member

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    Very cool software! Thanks much.
     
  7. mr88cet

    mr88cet Senior Member

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    Being in EV mode is not always synonymous with the engine being off. However, if the engine is off in EV mode, it’s not turning. That is the motors don’t crank the engine over with the drive wheels.

    Remember that the Prime has a sprag clutch that lets MG1 torque against the engine drive shaft, preventing the engine from turning.
     
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  8. Diemaster

    Diemaster Active Member

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    What if your SoC is 100% and going down a hill with regen braking? I've heard the ICE will turn over (no fuel burned) in D or B instead of the regen braking overcharging the battery.

    I live on a hill and when I leave the house and go down it, it feels like it engages the ICE when I press on the brakes. It's the same feeling as switching over from EV to HV while on the freeway (0% SoC or pressing the EV/HV button).
     
  9. jerrymildred

    jerrymildred Senior Member

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    That is one of the rare exceptions. Also, if the battery is getting too hot from going down the north side of Grand Mesa in Colorado, the car will switch to engine braking. Mine was up to 98% indicated SOC when the thermal controls said, "enough."

    Edit to add that I think the intent of the question, though, is whether the pistons normally move when in EV mode, and that answer is no, as @john1701a demonstrated and I have seen using my own OBDII apps.
     
    #9 jerrymildred, Aug 21, 2020
    Last edited: Aug 21, 2020
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  10. Trollbait

    Trollbait It's a D&D thing

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    That can happen, but when it comes to the question of oil life, just spinning the engine without fuel isn't really a burden to the oil. The heat of burning fuel is the main source degradation for the oil, and depending on climate, it is the main source of water in the oil.
     
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  11. ewxlt66

    ewxlt66 Active Member

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    I've had this question too...I've decided to do an oil change every 10k just like my non-plug in Prius' of the past. Cheap insurance or waste of money...not sure which.
     
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  12. Trollbait

    Trollbait It's a D&D thing

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    It's because Toyota says to do it, and you don't want to be out of luck on the very slim chance the engine dies under warranty.

    Past that, it's a waste of resources. When was the last time an engine needed repairs for extended oil changes?
     
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  13. ChapmanF

    ChapmanF Senior Member

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    should have seen the varnish in my Gen 1 when I had the valve cover off. I'm guessing it had run some extended OCIs in its past. Maybe that had never been the cause of any issue ... but then, I was chasing after a valve noise issue that was why I had that cover off in the first place, and it did seem that some of the cam journals weren't getting great lube.
     
  14. Trollbait

    Trollbait It's a D&D thing

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    Was that because of the oil, or because of the design?;) Heard of Ford engines getting that build up in that area, because the drains were too narrow. The fix was to change oil more often than recommended, or perhaps those with the issue weren't changing it as often. then Toyota tried blaming lack of changes for the sludge problem caused by inadequate cooling channels in the block.

    But we aren't talking about ICE cars, but a PHEV. Toyota calls for the same oil change interval regardless of car type, while hybrids and PHEVs won't be running their engine as often during those 10k miles as ICE models do. Oil at 10k miles in a Prime will be in better shape than oil than oil in a Corolla under the same conditions, and will have more consumable additives left.
     
  15. jerrymildred

    jerrymildred Senior Member

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    I just took a picture of my dipstick. Last oil change was 5,900 miles ago. Color doesn't tell the whole story, I'm sure, but it's still a little hard to see the oil. (I burned less than two tanks of gas over that distance.)

    5900mile-oil.jpg
     
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  16. PT Guy

    PT Guy Senior Member

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    There are several ways Toyota could have provided guidance to us for the engine oil, but they didn't. They could show us engine miles. They could show us engine hours. They could show us total gallons of fuel burned. They could have put oil drain limits on any of those ways, but they didn't. 10,000 miles is a simple minded way that every driver understands.
     
  17. Trollbait

    Trollbait It's a D&D thing

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    Honda and GM have a oil monitor system that tracks engine performance and climate. That is compared to tables of known consumption rates of oil additives under various conditions. The driver gets a light or message when the system determines an oil change is needed soon. Even Toyotas have a light to remind the driver.

    It was around 7500 miles for my HHR and Sonic, though some GMs could go over 10k miles under the conditions they are driven. The Volt could go up to two years between changes. With oil testing, it probably could actually go longer.
     
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