15w-40 in Prius

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Except that the electric motors only get energy ultimately from the IC engine, and the energy that the fuel imparts to the car.
 
Originally Posted By: JRed
Changed the oil in my Prius today. I've used 5w30 synthetic (whatever's cheap) up to this point, aside from a few thousand miles on Toyota 0w-20.

Put Rotella 15w40 in the sump. It'll be in there for at least 10,000 miles.

Drained out a Quaker State Ultimate Durability/Quaker State Advanced Durability mix that had been in for around 10,000 miles. I've stopped keeping tabs on it, really. Oh, and I didn't change the filter. Didn't feel like buying one, honestly. It has a Bosch DistancePlus or whatever they're called mounted right now.

MPG has been 48.1 - 48.3 over the last few tanks (5w30). I don't hand calculate anymore, as the Prius is fairly accurate as long as I remember to correct for tire size -- mine are 1% taller than OEM.

Guess my MPG is going to be terrible until I drain the 15w40 out.

Oh, and if you're wondering "Why in the heck did you put 15w40 in your PRIUS!?" ... It was free.


A get-back-at-everybody troll post? I'm on board.
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Originally Posted By: JAG
The Prius ECU is going to discover what horror you've subjected the engine to and will refuse to allow the car to budge! Just kidding. Yes, please let us know what effect it has on gas mileage.


Actually the Gen II Prius has been known to throw the red triangle of death with "error" on the screen if a really heavy oil has been in use.

It's not common but it can happen. I'd be leery of using a heavy oil like that. Heaviest I've used was 10w40 and only briefly, and it was a thinner synthetic.
 
Originally Posted By: JRed
No difference in MPG at this point. Prius is still reporting 48.3 MPG. I drive around 600-750 miles per week, usually 60/40 mix highway/city driving.


Thanks for the update JRed.

BTW. Do you have to reset the MPG calculations each time you fill up in the 2007 Prius? In my 2005 model it automatically resets all it's MPG data every time you fill up, but I think in later models they made the reset optional so that people could easily do multi-tank averages. Anyway, I assume that you know this and are resetting as appropriate.
 
My 2012 Prius C owner's manual browbeats pretty hard to make you want to stick solely with 0w-20. It allows 5w-20 for an oil change but you must change back at the next one.

A guy from Singapore showed what his manual says. He can use any 20w, any 30w, any 40w, and into the 50w, depending on temp.

I like the Mobil 1 0w20 and have no problem finding it. I'll stick to that. But I might use some 0w-40 some day just to make people on the forum uncomfortable.

I laud the OP for being on the pointy tip of the oil jug.
 
Originally Posted By: Mr_Incredible
My 2012 Prius C owner's manual browbeats pretty hard to make you want to stick solely with 0w-20. It allows 5w-20 for an oil change but you must change back at the next one.

A guy from Singapore showed what his manual says. He can use any 20w, any 30w, any 40w, and into the 50w, depending on temp.

I like the Mobil 1 0w20 and have no problem finding it. I'll stick to that. But I might use some 0w-40 some day just to make people on the forum uncomfortable.



Yep, the company knows it's readily available to us in North America and they really want the machine to achieve the best fuel economy possible. Might be a little hard to find 0w20 in Zimbabwe or something, so they "okay" whatever sour syrup they have out there. The Prius ICE is the definition of low-power-output and lackadazical duty.

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I laud the OP for being on the pointy tip of the oil jug.


Hear hear. It may be impossible to reap any better wear performance in a Prius engine IMO, but at least he'll have plenty of TBN reserve, resistance to ring coking and maybe a little general cleaning going.
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Quote:
No difference in MPG at this point. Prius is still reporting 48.3 MPG. I drive around 600-750 miles per week, usually 60/40 mix highway/city driving.


Interesting, keep us posted!

I usually like to switch cars calling for 20 grades over to a 30 grade at some point during the later years of the engines life.

I'm running Mobil 1 Extended Performance 5w30 now in the Mazda.
 
Originally Posted By: JRed
No difference in MPG at this point. Prius is still reporting 48.3 MPG. I drive around 600-750 miles per week, usually 60/40 mix highway/city driving.


Great news! Now that I see how much driving you do, the engine is hot most of the time, thus minimazing the MPG hit. I bet there is still some loss, in the range of 1% or so, but that will be undetectable in the real life.
 
Originally Posted By: buster

I usually like to switch cars calling for 20 grades over to a 30 grade at some point during the later years of the engines life.

I'm running Mobil 1 Extended Performance 5w30 now in the Mazda.


I agree. Seeing frequent oil consumption reports with 0W20 oils, I'm planing to switch to 5W30 from 0W20 after warranty expires.
 
Originally Posted By: uart
Do you have to reset the MPG calculations each time you fill up in the 2007 Prius?


Nope, it resets automatically each time you fill up. Pretty surprised at just how accurate it is considering how dismal most other cars are at calculating MPG.

One other interesting tidbit - when I once changed the oil with Toyota 0w-20 I was getting the best MPG the car has ever gotten (around 50.1 average). I'm surprised that moving thinner made a difference while moving thicker hasn't made a noticeable difference. Same time of year, same general summer time temperatures.

Perhaps if I didn't drive like I do I'd see a bigger difference. I drive on rural roads that have quite a few hills and I tend to set cruise control to 65 and just let it do its thing. I know I can get better gas mileage (49.5-50.5) by slowing down and driving without cruise control and not making the ICE scream at the beginning of an ascent.
 
Originally Posted By: friendly_jacek
the engine is hot most of the time, thus minimazing the MPG hit. I bet there is still some loss, in the range of 1% or so, but that will be undetectable in the real life.


This is my guess as well. I also rarely turn the car off if I'm stopping to go in a store unless I'm thinking I'll be out of the car for > 10 minutes, so the engine rarely has to warm up.

Granted, for the stops I leave the car on I also usually leave the A/C on auto and it does occasionally run the engine to recharge the pack. I figure the gas it's using to keep the car cool is less energy than it would use if I let the interior get to baking temperatures. Don't think it makes a huge difference either way.
 
I run Royal Purple 5w30 in my Prius which is my daily commuter. So far, the 1226 likes it the best.

I have used Toyota's factory 0W-20, Mobil 1 0W-20, GC 0w30 (over kill & too thick when hot) & at 91K a little heavier oil hasn't caused any decline in mpg. Still getting 50.2 - 50.6 mpg.
 
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Originally Posted By: SigQAEngineer
So far, the 1226 likes it the best.

What's a "1226"?
 
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Originally Posted By: SigQAEngineer
I run Royal Purple 5w30 in my Prius which is my daily commuter. So far, the 1226 likes it the best.

I have used Toyota's factory 0W-20, Mobil 1 0W-20, GC 0w30 (over kill & too thick when hot)



What is HTHS of Royal purple 5W30?

What generation of Prius?
 
Just checking in again, same MPG as reported by the in-dash display.

Low tire pressure light came on this morning, checked them at work and both rear tires were at 20 psi, fronts were at 25 psi. I had let some air out when traveling in Florida back in March and hadn't put any back in there since.

I'd expect with all of the tires back up to their usual 40 psi I might even see a little bit of an uptick in MPG.
 
I would keep an eye on the oil level, and if it is down a half quart or so do not add any for now. If you do not hit that 10,000 mark by the end of November, you might want to add a very low viscosity oil or some MMO to the crankcase to thin it for winter and you would have room for that. I know some parts of your State can see rather low temperatures at times.

I have done the same in my car, as in December a single day drive from the LA Basin to Tonopah or Ely up in Nevada, or Flagstaff in Arizona, can make my car see radically lower temperatures in a single day's drive.

Is this cool to do in a Prius? I presume it is, but I do want imput from others.
 
Originally Posted By: JRed

Oh, and if you're wondering "Why in the heck did you put 15w40 in your PRIUS!?" ... It was free.


15w40 Pfffft.....a real man would have put Redline 20w60 in there......
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