P0301 Code + oil high/smeared on 1 side of dipstick??

Don't do anything and see how long it takes for you to get a misfire code of some sort again if you do keep your oil where you've noticed it needs to be and just be ready this is not the one you want to try and keep with any serious foolishness.

 

I feel like my dipstick is always high on once side like you describe I would swap coils and spark plugs and then start saving for a head gasket or lower mileage engine. I would expect knocking from a head gasket to be the morning after a long drive when the engine and coolant has a chance to fully heat up and pressurize.

 

Often mis

From my experience on that code after you address the coil issue normally will tell you a bad cat converter code efficiency loss. As in platinum dust honeycomb clogged maybe cause of bad running oxygen/fuel levels overtime. Cake up. Also regular piston wall ware etc at that mileage. Causing piston slap or even maybe you have rod knock or a rod pin ware. Lots of moving parts .. all ware and tare in time old saying if it moves it breaks.

 

Just for due diligence, swap (say) cyl one and three coils/plugs, see if code changes to P0303. Still, with your miles, symptoms and code, it’s very likely to be head gasket failure.

looking through previous threads you’ve started, the cars been “ailing” for some time.

 

On these cars wouldn't you see coolant in oil if head gasket? A quick easy way to further investigation of your gasket- when looking at or troubleshooting coil problem when doing those take a flashlight and look at the top of the piston. If has NO carbon build up and "nice and shiny" can mean gasket failure cause the coolant getting in will "wash" the carbon build up off. You want to see carbon buildup at the top of the piston head. It's a normal occurrence of the combustion process.

 

In gen 3 head gasket failure is usually coolant leaking into combustion chamber.

 

Remember that if you bought your spark plugs off eBay or a similar marketplace site then they are likely counterfeit.

 

The oil on one side of dipstick when I see that usually means a quart or so low. Your engine is probably burning a little oil. Which also can cake the catalytic converter. Which on these cars is top ten most expensive on the market(last I looked 2400 roughly I think). Right up there with Ferrari. I think there's a Ford truck on that list too. Which stinks. But we gotta take the good with the bad right? Still love my Prius.

 

Those are counterfeit plugs. Real ones would take 2 million miles to wear that bad.

 

Yep. Real Iridium basically doesn't wear.

They only lasted till whatever mileage they were at 1.5 years ago.

 

The centre electrodes look odd, and very worn. They shouldn’t be worn at all. Here’s the factory plugs from ours, replaced at 12 years, and roughly 90k kms:

 

They all look bad! HUGE gap.
I would agree with Post $14, cheap chinese copies! With only 80,000 miles on them.
I'm surprised they lasted that long.
Either go to autozone and get Bosch plugs, or the dealership where you are more certain
to get the REAL plug.
After 125,000 miles, you should only see very very minor wear. Iridium does wear, but it takes a while.
Some have gone 200,000 miles on them and only showing minor wear.

 

Most certainly! They are all black. They likely aren't always firing...

Autozone didn't have the Bosch plugs I get, so I settled for ngk. After 5000 miles one started
to misfire on #3. I switched #'s 3 and 4, and the misfire changed to #4.
I replaced them with Bosch. No issues since.