Burning oil problems solved - how to clean piston rings (oil & compression) and prevent catalytic converter problems
First: I had a 2007 Prius with 272 thousand miles. It was burning so much oil I always had several quarts of oil in the car. It was burning about 2 quarts of oil every time I got gas and the oil got dirty very quickly and the plugs fouled. Now it burns less than 1 quart of oil every oil change and the oil is still fairly clean at 3,000 miles after last oil change. A HUGE IMPROVMENT! It just got an overnight soak. A fast clean out (poured a flush product and ran engine for a few minutes before next oil change) and some Techron.
Prius 2007 109k miles: The top left picture above shows the top of a piston at the beginning of a Seafoam soak and the top right at the end of the soak. Besides the carbon looking thinner the white spot is where the carbon had pealed off exposing the bare aluminum. The main purpose of the soak was to improve the performance of the piston rings. The lower picture to the left shows the same piston after 600 miles with Techron being added to the gasoline. Notice that some of the carbon appears to be burned off. The piston is much closer to the top of the cylinder so the image is different but it is the same piston.
The pictured piston is in a 2007 Prius engine that had 109 thousand miles on it. After cleaning the rings the engine runs much quieter and there is no shudder when it starts. The purpose of this soak was to reduce oil burn so the catalytic converter did not go bad at 200 thousand miles and to promote the life of the engine. The plugs were not fouled.
A Prius starts burning oil around 100 thousand miles by about 170 thousand miles the Catalytic converters start to go.
Oil burn is a bad thing because:
- It will coat up the catalytic converter till the point where it stops working and is often needlessly replaced. If you replace it without fixing the oil burn you will have to replace it again.
- You will loose compression and you oil gets dirtier faster shortening engine life.
- You have to add oil between oil changes.
When it gets really bad:
- You spark plus can foul up.
- You can run the engine oil dry and destroy the engine.
- Have to replace the catalytic converter. Maine, New York and California have restrictions on after market catalytic converters. As a result this can cost you thousands of dollars in those states. Plus if you
- Waste a lot of money on oil and cause unnecessary air pollution.
My 2007 Prius 272k miles on it was burning almost 2 quarts of oil with every tank of gas. I was very lucky I had not ruined the engine by running it dry. I always carried spare oil in the car. IN SHORT I HAD NOTHING TO LOOSE SO I TRIED A METHOD THAT DIRECTLY ATTACKS THE PROBLEM. It worked! I now am not burning oil and the oil is staying clean. I tried everything to clean out the Catalytic Converter and although it worked a little better but I could not recover it well enough to keep the ODB II trouble code of P0420 - Catalyst System Efficiency Below Threshold appearing. I replaced the cat but in a state with California emission laws it is very expensive! No matter what state you are in it is at least a two to three hundred dollar expense plus the expense of buying extra oil. In short do this at 100k mils or at least before 150k miles and you can avoid these expenses.
Basically I poured 4 oz of seafoam down each spark plug hole and let sit at least overnight. If you let it sit overnight disable the fuel flow, and spark voltage and crank the engine to get out the Seafoam in the combustion chambers. If you let the Seafoam soak into the engine for two days the piston tops will by dry and no need to crank the engine. With either method drive no more than 25 miles with no heavy acceleration and get the oil changed.
I have details specific to the engine on a 2001 to 2009 Prius and Prius C. There are enough pictures that even if you have never change spark plugs before you will be able to do it.
If you want our detailed instructions just buy anything from this store or you can download it from this page.
"The guide is super helpful." K.V., Los Angeles, California