How serious is the gen 3 oil consumption issue?

First off... welcome!

Since you're aware of the potential problem, I assume you're also aware that most 3rd Gens don't excessively consume oil, and that there seems to be no correlation among model years, miles, etc.. For instance, my '13 V wagon was burning a quart every 700 miles when I bought it at 93K miles. (I didn't know since I bought it from a used car dealer) Others on this site have 200K + miles with no oil consumption. I'm not aware of anyone being able to determine a reasonable cause and effect.
It's also worth noting that with my V, it burned oil at that alarming rate only when driven at high highway speeds -- 75-80+ mph. When driven around town and at rural road speeds, it seemed to burn almost no oil. It's also worth noting that the oil consumption doesn't seem to effect the way the engine runs. My V now has 180K miles (which equates to about 30 GALLONS of oil burned and exhausted through the tail pipe!) The engine has always -- and continues to -- run perfectly. And because of a job change, the car is no longer driven at highway speeds. And guess what? The oil consumption has stopped.
I think your logic is sound: if it's not indicated in the service record, and you think the owner is honest that he/she is unaware of an oil consumption problem, then it likely doesn't exist.
So with the potential oil consumption issue out of the way, all you have to worry about is the clogged EGR, head gasket, inverter failure, and ABS actuator.
Assuming you work 5 days/week @ 100 mile daily commute, you're going to put 25K miles/year on your car just going back and forth to work. Add to that any weekend travel, errands, and gereral running around I would think you'll be closer to 30K/year. At that rate, you'll put 100K miles on in a little over 3 years... not 5-6.

Is your commute mostly highway or back roads?

Will you DIY some of the maintenance?

 

Another thing to think about is the relatively low cost of oil. I just looked at Amazon and FIVE QUARTS of a top brand oil (Castrol) full synthetic is under twenty bucks. So even when @tvpierce was burning the most, the cost is about $100 for 20,000 miles, give or take.

 

buy the corolla, it's not the oil consumption, it's the head gasket

 

Are the Corolla's immune? Mayhaps a different EGR system? I know, drifting...

Addendum: yeah looking on McGeorge Toyota Parts, does not seem to be EGR components of any sort. I'd suspect there's something, but rudimentary?

 

no idea, check corollachat

 

Quickly searching toyota official parts too, no "EGR" found. And I found one forum that says "no egr, variable valve timing used instead". Interesting...

 

My car burned no oil until it was close to 150k, five years in. My first failure was the inverter, completely stranding us out of the blue. Toyota eventually stepped up and covered it as a design flaw. Other than that, it was good through 200k but the hv battery was on it way out. Later it was the brake actuator, at least $2500 sometimes $4,500 from the only source, the dealer. Just recently, Toyota is covering that on the v for ten years from start of service. You would probably be covered into late 2022 or sometime in 2013, depending on when the car was purchased.

It is clear the 2010-2014 Prius engines had bad pistons and rings. So bad Toyota would replace them under warranty if early oil consumption was high. EGR design is poor until gen4 and the intake manifolds fill up with oil from the pcv. High speed driving and carbon buildup compound issues. All of these things combined with too long 10k oil changes often cause head gasket fails, sometimes complete engine fails.

You would have a good chance at 200k and maybe incur only one $3,000 repair depending on your location and driving speeds. The hv battery is likely if you are in a hot southern state. Repairs are less in some cities that have good hybrid mechanics independent of dealers. It is always best to include your location. If it were California, there are many low cost resources. Louisiana, maybe not. So be sure the price is on the low end of the kbb range to accommodate. Obviously the previous owner only put 12k miles a year on it, not the 30k you may experience..

 

Delete

 

Without knowing current owner driving habits and not mentioning being a DIYer to put in a catch can, the intake manifold and egr cleaning, maybe get another 50,000 miles.

and save a few more grand after buying the car and prepare for hv battery failure.

or just get a Corolla because saving gas cost money.

 

Except..., driving a Corolla feels like slow death.

 

I was worried that my Prius was burning .2-.3 quart oil too At 5-6K OCI while using SuperTech oil . Although Super Tech’s cleaning ability was very good. I turns out now that I switched to Penzoil Platinum and most recently Napa FS oil there both times I checked the oil level at exactly maximum mark on the dipstick. Pennzoil came out pretty dirty. Currently Napa oil looks still fresh at 4K. With Napa 0w-20 engine runs quieter than before.

 

I'm not so sure on the better engine in the gen4 just yet.

I installed an oil catch can on our 2019 Prime at 21k miles, did the oil change at 30k and here's what I found in the can:



So there is still blow by even for an engine that runs ~33% of the 10 k oil change interval, given my EV % is 67%.

At 120k when I pull the spark plugs will be the true "proof is in the pudding" moment.

 

Where did you install it? With zip ties also? Zip ties on mine is still holding up.

 

Up front and top side:

Oil Catch Can

The Prime isn't conducive to a lower mounted catch can due to the front cross member position.

But I made due.

 

Often, when I'm asked about whether or not it's a good idea to buy a ten-year-old car I tell some people (who don't DIY) that they may not be able to afford to drive a cheap car.....

Same sorta thing here.
Priuses are one of the CHEAPER and MORE reliable cars to own for 10 years or about 200,000 miles......if YOU own them for that length of time and keep up with MAINTENANCE.

Buying an 8-10 year old Prius is sorta like buying an older home.

Worthwhile?
Sure!
Just don't confuse that with easier and/or cheaper.

YMMV....

 

What if I using 2 cans and the first cans with breather, and hope to cooler down oil vapor in 2nd cans.

 

At 80,000+ miles, my '13 PIP uses no oil between 10,000 mile changes, at least not enough to tell from the dipstick.