Which oil do I switch to if I am burning 1 quart/5k miles (2010) Prius

Growing up in my days, “fresh” meant cool or hip

 

I remember it meaning something more like impertinent or disrespectful.

 

All I got is "Fresh Prince of Bel Air".

 

Will Smith definitely would argue that “fresh” means cool and hip.

At least back in the day.

 

Haha, yeah it felt a little weird typing that out, honestly.

 

Also, another thing to add to this thread. I also own an Acura MDX which also can suffer from excessive oil consumption due to coked piston rings. This is because of the TCU programming favoring low RPMs to increase gas mileage. Several owners have found that the occasional aggressive driving (high rpms and large load) have decreased or eliminated their oil consumption problems.

It kinda goes against the natural tendency when driving a Prius, but once the ICE is warmed up, maybe don't be shy to put that ICE under a little stress, build up a little heat to help burn things off.

Luckily for me, I have terrain (mountains) that naturally have me putting a good load into the ICE, so I'm not terribly worried about this issue.

 

It sounds plausible, but nothing's "burning" in the cooler. I think it's "death, taxes, and now: 3rd gen EGR clogging".

 

Then why do some clog much earlier in life than others??

 

Did you know that the engine of a Prius runs under relatively constant load most of the time, and varies power by changing engine speed instead?

 

I don't think there's anywhere near enough data on that. Not saying driving style isn't a factor, but I suspect it doesn't matter that much.

 

I'd say that is inaccurate.

The Prius first tries to accommodate an increasing load by varying the CVT. Once the CVT can no longer adjust to handle the load required, then it transfers the load to the engine, this would be seen as an increase in RPMs for the ICE. So, yeah, changing engine speed means that it is changing the engine load.

 

Still confused, I see.

 

I think you're just unaware of the entire range of loads that a Prius can operate in. If you have flat driving all the time, sure, there's a narrow band of engine loads that the car will operate in, but if you have hills at all, the engine load will vary greatly if you are maintaining speed.

On a flatish road, if a headwind or slight uphill grade begins then the Prius can maintain a similar engine load (like you said) by changing the gearing that the CVT is utilizing. I believe this is what you are talking about, correct? This would be seen as a shortening of ratios from the CVT and an increase in RPMs from the ICE. Inversely, if a tailwind or slight downhill comes along it can do the opposite.

The problem is, the amount the CVT can adjust and maintain speed is pretty small. If you get a real hill, a constant engine load will only slow you down, at some point you can't adjust the CVT enough to maintain speed, you either run out of RPMs or run out of gearing.

Once you (quickly) blow through that range of adjustment, the CVT will adjust the gearing so the ICE is at an "optimal" RPM and engine load increases to maintain speed.

When it comes down to it, if you are maintaining speed, then if the external load increases, then the engine load increases.

To simplify it more you can assume that fuel consumption is proportional to engine load (it's not really since engine efficiency varies, but it's a good-enough generalization here). So, when you see you handy-dandy fuel consumption meter drop lower, your engine load has gone up.

If you still disagree with me, explain your side and add knowledge to the community instead of just making a one-sentence quip and leaving. I'm open to learning about something that Toyota engineers have achieved that I'm unaware of, if that truly is the case.

Edited to add: Yes, I know that the electric motors can help make up the extra load, but there is no free lunch, a hilly ride will eventually deplete the stored power in the battery and the ability to reduce ICE engine load by using the traction motors will be diminished. So, the traction motors can delay the increase in engine load, but not eliminate it. And if you floor it, there is no avoiding it no matter how much battery power you've got stored up.

 

By 'load', do you mean torque?

 

Yes, that's conventional usage. Nepbug seems to be using that term to mean power output. See the "Operating line" of the engine performance plot that is a sticky in this(?) subforum. That shows how over a range of moderate (not at either extreme) of power demand, engine speed varies considerably, while torque (and incidentally also manifold absolute pressure, which is not shown) varies through a narrower range. I notice MAP tends to hover around 12.x psia much of the time, as the programming follows that operating line.