[Isaac Zachary]

Originally Posted by S Keith

it's a Prius. Those that don't burn oil are rare. It's the nature of the beast. When you start and stop an engine 30 times a drive, you get a lot of heat cycles on it. Crap accumulates in the rings and grooves, etc. Folks, including myself, have had success soaking the cylinders with Berryman's B-9 (chem-dip) down the spark plug holes for 24-48 hours. Neighbor has 300K+ on his 2007, and it was GUZZLING oil - about 1 qt/400 miles. After a treatment, it cut oil burn to 1.5qt/5K mile.

I did it to my ratmobile, and I haven't had to add oil for about 2000 miles with it just below the top mark of the dipstick. It burned 2qt/5K mile before.

If you have P0420, it could be solely due to your oil burn rate.



Shortcut: Discharge the battery in "N" until the HV battery isolates. Let the battery sit for a full 48 hours. Check all module voltages. Modules lower than 0.05V below the highest voltage module should just be replaced. End modules can be up to 0.10V below the high module.

"newer modules" - Did you test those too? Unless you're buying from reputable sources, you may be getting garbage.

Unless it's a high end unit capable of about 20A discharge, it's likely not useful on its own. You need to add a ~60A load test. hit the module with the 100A 12V load testers and record voltage drop. Compare all 28. Discard the outliers.

One more thing about Gen3 Prius... they EAT engines. You may have heard about head gasket issues, but it's way worse than that. Without fail, after another 10-20K miles, need another head gasket, or a thrown rod. If a Gen3 has a bad head gasket, it needs a new engine. Period.

DO NOT FOLLOW TOYOTA'S RECOMMENDATION TO CHANGE OIL @ 10k MILES IF USING SYNTHETIC. STICK WITH 5K MILES.

I'll try fixing the rings. But I'd also like to get a scope and see if the cylinders are damaged (which is what happens if the rings seize.)

I tested the newer modules and they had more capacity than any of mine.