My '07 Prius has been consuming roughly 1 quart per ~1000 miles for the last 100k miles or so. I figured a piston soak was relatively low effort, low cost, and (hopefully) low risk. I've already replaced the PCV several times and run Castrol Edge high mileage on 5k OCIs. I removed the spark plugs and was greeted by this:
This was just after removing the plugs on a still warm engine. Tops of pistons 2/3 look pretty awful compared to 1/4 (to me anyhow).
I ended up going through two 12oz cans of Berryman's B12. I put a few ounces in each cylinder and rotated the crank by hand a few revolutions, poured a bit more, replaced spark plugs (loosely), and waited a few hours. Rinse, repeat until I was out of chemtool. Let it sit overnight and dumped the now pitch black oil and replaced with fresh. I also replaced the PCV and cleaned the MAF/throttle plate and whatever oil/etc. had accumulated beneath the throttle body in the intake plenum. Blew any remaining chemtool out of the cylinders, threw the old plugs back in, and started it up.
Billowed smoke for a few minutes but ran well otherwise. Drove it like a maniac for ~20 minutes, let the engine cool, and replaced the plugs with fresh ones. I accidentally deleted the "after" video I took, but all of the pistons looked like the top of #4. It certainly seems to run better, but I'll report back when I know more in regards to oil consumption.
This was just after removing the plugs on a still warm engine. Tops of pistons 2/3 look pretty awful compared to 1/4 (to me anyhow).
I ended up going through two 12oz cans of Berryman's B12. I put a few ounces in each cylinder and rotated the crank by hand a few revolutions, poured a bit more, replaced spark plugs (loosely), and waited a few hours. Rinse, repeat until I was out of chemtool. Let it sit overnight and dumped the now pitch black oil and replaced with fresh. I also replaced the PCV and cleaned the MAF/throttle plate and whatever oil/etc. had accumulated beneath the throttle body in the intake plenum. Blew any remaining chemtool out of the cylinders, threw the old plugs back in, and started it up.
Billowed smoke for a few minutes but ran well otherwise. Drove it like a maniac for ~20 minutes, let the engine cool, and replaced the plugs with fresh ones. I accidentally deleted the "after" video I took, but all of the pistons looked like the top of #4. It certainly seems to run better, but I'll report back when I know more in regards to oil consumption.