Motor oil is the lifeblood and sole source of lubrication for your motor. The job of the motor oil is as follows:
1. Cool the lubricated parts in the engine.
2. Clean the lubricated parts in the engine.
3. Protect the lubricated parts in the engine.
4. Transfer power in the hydraulic parts in the engine.
Fuel dilution, moisture, soot and heat all affect the motor oils ability to do it’s job, so it pays to keep your motor oil cool, clean and dry. With that said, your piston rings are the only line of defense between combustion gases and your motor oil.
Invented by John Ramsbottom in 1854 (before the internal combustion engine was even invented), the piston ring is a seal. The job of the piston ring is to:
1. Seal the combustion chamber and minimize the loss of gases to the crank case.
2. Improve heat transfer from the piston to the cylinder wall.
3. Help maintain the proper quantity of oil between the piston and the cylinder wall
4. Regulate engine oil consumption by scraping excess oil from the cylinder walls
When you look at the job of the motor oil (to cool, clean and lubricate the engine) and the job of the piston rings (to seal, transfer heat and meter the oil), it is easy to see how they play complimentary roles. The better the piston rings do their job, the easier it is for the motor oil to do it’s job, and vice versa.
In over 15 years of reviewing used oil analysis reports, I’ve never seen low engine wear when the oil contamination levels are high. In fact, the bad wear results generally coincide with high levels of fuel dilution and other combustion related contamination.
However, when was the last time you thought of motor oil and immediately thought about piston rings?
When you think about motor oil today, the first thing that probably comes to mind is Zinc (ZDDP), and that is understandable. The issues related to the changes in ZDDP levels in motor oil have been the headline story in our industry for over 15 years, so it is understandable to think zinc at the mention of motor oil. However, there is more to motor oil than just ZDDP – just as there are other parts in an engine besides the camshaft. Today, we have several specialty oils designed to protect your engine, but these oils can’t do their job without the piston ring doing it’s job.
In simple terms, the better the piston rings seal the gap between the piston and cylinder wall, the less combustion blow-by gas (which is hot, full of moisture, fuel and other nasty chemicals) gets into the oil. The bottom line is that better ring seal means better oil life and performance, which means longer engine life. That is why your piston ring is your motor oils best friend!