Oil change every 5K to prevent excessive oil consumption ?

Maybe the soot's coming through the EGR, Intake manifold, dumping into the combustion chamber and ending up on piston rings? The rings foul, accerating oil burning? Oh joy...

 

Yes, that was what I was imagining. Though, how much gets past the rings into the oil is not known. That's why I was proposing an engine oil soot analysis, especially for a higher mileage car like mine. If it's not getting past the rings into the oil, then I'd stick with the 10K mile oil change interval. If it's getting into the oil, that could persuade me to do more frequent oil changes.

I'm about to open up my intake manifold again at 168K miles (and check the EGR valve and cooler) because the engine is hesitating again. I did it initially at 151K miles before any issues (I think), and the passages were partially clogged with soot, with oil mixed in turning it to sludge on the passenger side. At 158K miles, I had hesitation from misfires and insufficient EGR flow that was resolved by a new EGR valve (under the enhanced warranty). All was well for 10K miles until recently with the hesitation/possible misfires, though no check engine light has come on yet. I don't know if the dealer cleaned the EGR cooler at 158K when the valve was replaced. If not, what was in there and more has blown through back into the intake manifold, and might be causing the valve to stick. I'm not worried about the head gasket because the coolant level hasn't moved and I don't see oil in the coolant or coolant in the oil.

 

I've been reading up on the EGR, following the discussions here, closely. One big advantage of our low usage, all you pioneers will have it all sorted out, when (and if) I get to that mileage where EGR starts to clog. A couple of things on my shopping list:

E8 Torx socket (for removal of the stud fasteners on the EGR cooler)
Purple Power

The latter's a degreaser/cleaner that is apparently the bees-knees for cleaning EGR coolers, effective and fast enough that you can likely avoid getting a second cooler*.

We bench-test diesel EGR Cooler cleaning solutions

I'm thinking to look at our EGR cooler, and the EGR valve, pipe and intake manifold, at around 10 year mark (fall, 2020). We'll likely only be around 100,000 km by then, but abiding by the date interval, it'll be time for spark plugs and coolant changes as well. What with removal of the wiper motors and cowl, and draining coolant, seems like an opportune time to inspect the EGR cooler.

* I've seen EGR cooler prices from $35 US, for a used one on EBAY (inflates to $90+ Canadian, with shipping exchange and duty), through mid-$200's US for a new one through online US retailer, to (wait for it): $596 (Can), retail for the new part through local Toyota dealership parts departement. Their best price, a mere $499.

 

I bought a E8 Torx socket at my local Napa last week in anticipation, based on the service pdf that you posted a while back. Just discovered the new activity in the 4 quarts down thread... good stuff.

 

Sorry. Soot in (diesel ) oil and piston ring groove deposits are 2 different things. Piston deposits form from:
A. Hot pistons
B. Low quality oil
C. Too long OCI
D. Poor oil circulation in groove (plugged oil return hole)
E. All of the above

 

I've been reading this thread looking for an explanation of C. Can you provide one? Is this common knowledge (I'm not a mechanic)? What changes in the oil during use to cause this? You say earlier that it can't be measured in a $10 test. Why can't a change in oil content/properties be measured? What about more expensive lab tests?

 

has anyone dissected one of these bad boy burners, to see what actual damage there is?

 

those are good questions, but it's not easy to explain. let me try. when pistons are too hot from combustion, oil will oxidize and polymerize, turning into solid varnish. that "damaged" oil is instantly removed from circulation and will not show up in your typical UOA. some labs provide oxidation value, but they are not calibrated to any universal units and the numbers are arbitrary and all over the map, dependent on lab instrumentation and even type of oil tested (matrix effect). obviously, lower quality oils (mineral) and older used oils will be more susceptible to oxidation. using quality synthetic oils that 0W20 typically are should prevent varnish from happening if not for one little detail. the most common synthetic oils are made from group III base oils that have poor solubility due to their saturated bounds. for that reason, group I or II base oils (mineral oils) are added to those oils to keep the additive package in solution. hence, most "full synthetic" oils on US markets are really just synthetic blend oils.

now, using the 0W20 viscosity makes things a bit worse as the oil film is thinner with lower viscosity oil. while this makes the job for oil control rings easier in the short term (less oil to scrape from cylinder liners and less friction, too), in the long term it harms them as less oil circulation in piston grooves means more propensity to form deposits. i personally don't claim there is a huge difference of new 0W20 oils vs the traditional 5W30 oils, as older 5W30 oils used to shear down to 5W20 oils all the time.

one has to understand that prius was engineered to optimize fuel economy. that means that some other qualities had to be compromised. if you think about it, slow oil consumption growing after 100,000+ miles is an excellent built in planned obsolescence feature.

it has been done. all you need to do is to search.

 

If you're looking to do it in 2020, I'd swap you coolers and valves. Mine should hit 200 k miles on 2019 / early 2020 so it'll be freshly cleaned then.

Road trip for a meet up?

 

After this weekend, @Aaron Vitolins might be able to provide pictures and an answer!

I'll be tuning in this weekend as the work begins and pictures are available.

Here's to optimism this weekend.

 

Thanks for the invite, but I'll give Purple Power a try. From that review I linked, it looks like a few hours soak will do the trick. And, our car is definitely not a must-have. It can sit idle for a day or three.

 

I meant more for cooler removal.

Seems like your the one man band up there.

 

Oh, gotcha. Yeah, did I hear you mention to back the studs right out, that maybe makes it easier? This won't happen for three years too, lol.

 

I changed the oil and filter at 1k and at 5k and every 5k thereafter. When I sell the car, it will be one of the differentiators I place in the ad.

You want oil talk, wander over to Bob is the oil guy

 

If I disclose my oil change interval they'd have me committed.

I'm following the Canadian 6 month criteria, but my kms are considerably less than 8000.

 

Even the K&N ones are less than $6 a piece on Amazon. I'm not messing around with going 10k on an oil chance. My car is how I make my living. Plan on keeping it for a million or two.

Posted via the PriusChat mobile app.

 

All these oil change discussions are confusing. To each his own. most people will be well served by just doing what the owner's manual recommends for their specific year of Prius, and their driving conditions/amount of use.

For my peace of mind (and driving style/location) I prefer a more frequent oil change & new filter - every 5k/6mos. I consider it cheap engine insurance. I plan on keeping my Prius for 15 years. I will also change the cabin pollen filter and the engine air filter every 12 months. both were very dirty on my 2016 Prius. OEM filters can be purchased cheaply online.

 

Seems to me that the factors that lead to engine deterioration and excessive oil consumption are diverse. And also the pace of deterioration of the oil in the engine itself will be affected by factors that go outside of just mileage.

So I don't know if you can say that a 5K interval is a magic bullet number.

That being said? I think if you own and operate a vehicle with a known propensity to develop this problem? I always say, Oil Changes are IMO very cheap insurance.
I tell people...embrace what you think works. What makes you most comfortable. I'm very hesitant to ever recommend anyone exceeds a manufacturers recommendation...but doing Oil Changes more frequently and sooner?
If you can afford it? Why not?

When I was a kid...nearly everyone operated under the common mythology that Oil Changes should happen every 3000 miles. Even without synthetics, it was ridiculous and really just a money maker for service departments and quick oil change operations.
But I did it. At least 4+ times a year.
So every 5000 miles? Why not? Would nearly seem like old times.

 

and you could pour the old oil down the sewer without guilt.

 

When I was a kid there was a place behind the gas station where they dumped the used oil and filters.

The garbage truck dumped into a chute, straight into the river, below the dam (Powell River). I was starting to think that mighta been a false memory, seemed so bizarre, then was reading a history of the place and yup: that's how it was.