New spark plugs and carbon buildup.

The article below can be found online at http://www.motormagazine.com:
Overfilling the Prius crankcase is another basic mistake that increases drag, reduces fuel economy and may trigger the no-start DTC. By the book, an oil and filter change on this engine should require barely four quarts of oil. Considering the potential consequences , it’s worth taking extra care to be sure you don’t overfill it. For instance, some techs routinely pour in three quarts. Then they warm up the engine and top off the crankcase a wee bit at a time, finishing up with the oil level a little bit below the upper mark on the dipstick. They argue that it’s smarter to be a little below full than over it. The approach has worked well for them. (Reportedly, there have been cases where thicker oil and/or overfilling have actually prevented a Prius engine from restarting. Forewarned is forearmed!) The Prius engine is an Atkinson cycle design. Its unusual valve timing allows reversion to occur, leaving some residue inside the intake manifold. This is normal. However, an overfilled crankcase can leave puddles of motor oil inside the intake manifold. Sources said that experience is the only way to quickly distinguish the difference between normal residue and abnormal puddles of oil here.

I would not believe it based on experience with dealerships. I had records that the previous owner paid $800 for the 120 k miles which included replacing spark plugs. Well I had to change them because they never did.

This is somewhat unusual for a Prius. Yes it happens often in Audi and Porsche engines but for a Toyota is not common.

 

Do you run any additives in your fuel?

 

To me, that definitely looks like ash from burned motor oil on that spark plug.

We've had a couple Prii, and I've always kept the dipstick level halfway between the "add" and "full" marks. As long as the engine doesn't consume oil, I consider that a safe practice.

 

There is always oil in the bottom of the intake. It Was there when I bought my 07 new and is always there every time I looked. And my oil is right at the top mark on the dipstick. That oil is very normal for a G2.
Its part of the Atkinson cycle weirdness of the motor where the closing of the intake valves are delayed and that tends to push combustible products back into the intake. The G2 uses a extra large plenum in the bottom of the intake to quench that but still sucks some oil into it.

A G2 takes 3.6 quarts of oil with a new factory filter.

The op never stated the mileage on the car I would bet 180,000 + miles or more. Those are the original plugs. I'm sure the seller told you he just replaced them.

The borescope pic does not look that bad depending on your unannounced mileage. The car probably has been run on dyno oil all its life or worse dealer oil changes. Prove me wrong pull the valve cover off and take pictures of the valve train. I bet there's some nastyness under that cover.

In fact you should have pulled the valve cover off anyway and replaced the valve cover gasket because most leak at the age at the spark plug well hole and fill up the spark plug wells. Check for rust deposits on the side of the plugs or use your borescope and look in the wells. Should have done that first before you pulled the plugs.

I would check the throttle body as it probably needs a clean.

Here's a borescope of my cyls at 140,000 miles been on synthetic oil all its life. And a shot of oil filled spark plug well from failed valve cover gasket.

 

Check the plug gap. If it's out of spec, it would indicate that the plugs have a lot of miles on them. If they're well within spec, they're probably newer. Patrick Wong says on another thread that spec is 1.0 mm to 1.1 mm; you may want to verify that.

Directing water mist into the intake while the engine is running can clean carbon out. There are a number of YouTube videos illustrating the method.

 

Why would you not keep the oil at the full line? Tiny motor only holds 3.6 quarts. It needs every drop.

 

I changed the plugs on my car At the same mileage and they looked much better than those plugs.
Makes me think the mileage is phony. Really easy to change the mileage just replace the combo meter with one with lower mileage. Combo meter failure and rep,acement is very common on this site high failure item.

your pictures of the piston is not that bad I would not be concerned about it.

 

Yeah, slightly under 4 US quarts, with filter change:

I'd be inclined to just drain thoroughly, then just put in the spec'd amount, verify the level a day or two later, when it's settled down. I've found if I start second-guessing that, checking the dipstick right after the oil change (even after running the engine a bit), I end up overfilling some.

 

I disagree. The dipstick marks specify the high and low safe limits. The Atkinson engine has a habit of blowing oil into the cylinders if the sump is too full. Keeping the oil level below the full mark mitigates that.

I follow Toyota's oil change recommendations using Mobil One 5W30. That interval is quite conservative IMO. Our car has nearly 130,000 miles (100,000 under my watch) and doesn't burn a drop.

I agree that the ash deposits are nothing to worry about. And I do suspect it's ash, not carbon.

 

The computer. Where’s “the computer”?

It’s stored in the combo meter which is the dash display
The one I bought has 20000 less miles than the original combo meter.
Some are able to put your original mileage into another combo some are able to repair your original combo
I got good deal on a repair from Matt at Texas Hybrid thanks matt just so happened it was 20000 miles less

 

Wrong again.

 

Odometer fraud, with failing all-in-one digital displays, is almost impossible to avoid. We progress.