2012 Prius C 10k mile oil analysys

It's likely you'll find a noticeable decline in MPG if you overfill your car with even just alittle too much engine oil. If you always overfill you can expect your throttle body to get gummed up and damaged, as well as possibly shorten the lifespan of your catalytic converter... PriusChat is loaded with threads of people dealing with diagnosing the red triangle of death simply because the oil change people always put four quarts rather than 3.5 quarts, which is the standard.

 

How did the report look at 1500 miles?

EDIT: Nevermind! I see the second column.

 

I wonder if Toyota increased engine oil displacement to address this issue? Toyota dealers have insisted on putting in 4 quarts even when displacement calls for 3.5 quarts... There's lots of reasons for this I guess...

It's kinda interesting the that a Prius C is smaller in so many ways, yet bigger when it comes to engine oil.

 

When the manufacturers put two marks on the dipstick, I think implicit in that is mid-way between those two marks is the sweet spot. That's in a perfect world, with an engine not consuming any oil. FWIW, no dealership's service department will agree with that. They treat the full mark kind of like a lot of drivers treat the speed limit: a starting point.

Anyway, I like when the level's around the 3/4 mark, a bit below the full mark, but a ways to go before you need to be concerned.

FWIW, the previous fill I did I was more-or-less on the full mark. And the latest fill I managed to keep it about 3/8" lower. Didn't seem to be any significant change in mileage. I'd suspect it would take gross overfill, say at least a quart (liter) before you'd start to notice anything.

 

+1
Three reasons for filling to the full mark.
1. If something goes wrong and your engine starts to consume oil fater than normal, you have more time before it turns into a disaster.
2. More oil means more additives and more oil to wear out, important for long change intervals.
3. More oil means more time in the pan which gives a little help to oil cooling.

 

More oil also means more likely a customer will not complain about not getting enough oil...

But as someone who saw mpg drop because of too much oil, I'll do all I can to keep the oil level in the center of the sweet spot... Favorite part about Prius is all the wasy to fine tune the car and optimize as much as possible every sweet spot.

 

Many threads on Prius Chat suggest that even just a 1/2 quart over can create problems...

 

From the dealership service department's perspective it does make a lot of sense to fill to the top line:

They don't know if the engine's consuming oil, and any customer who's paid the bucks for an oil change is going to be upset if they have to top it up shortly. OTOH, for DIY'rs...

 

Usually, pulling the sample from the pan invalidates the results. I've seen really bad reports from people who tried it, but your sample is the exception. Your iron is only 1ppm/1000mi which is as good as it gets. Nice.

 

I've been using 4 qts., which slightly passes the full mark, for 226k. Not a damn noticeable difference. No need to worry people.

 

Very good used oil anlysis numbers. I used to post my results and as long as you properly break-in your Prius and switch it over to synthetic before 10,000 miles, the motor will run a long time with little to no oil consumption.

Even keeping the oil level halfway between fill and full, I still had some gunk on the throttle plate and deposits on the mass air wires. I blame that on short trip operation. My FJ does the same thing unless it is always on the highway.

The first two oil changes I had done at the dealership and they always managed to dramatically overfill the oil. Half an inch over the full mark

 

Thanks for sharing the UOA, looks good. IMO there's no need to change it for another 10k miles.

Just for clarification, you're using Mobil1 0W-20 AFE?

 

Your wear metals are already excellent and on par with Blackstone's Universal Averages, which means the engine has stabilized and is broken-in. The additive package looks to be good-to-go for quite a bit more distance. I see no reason to do short intervals anymore unless you just want super-extra piece of mind.

What would 5w-20 get you other than more friction when warm [cold]? You're not doing track days with the car so your oil temps aren't higher than typical, and you don't live in a hot climate to rationalize thicker oil. I'm just curious as to your rationale or proof; if I'm wrong let me know.

 

5W-20 has more drag when cold. When at operating temperature it acts the same as 0W-20.