The short answer: Simply put, piston rings form a seal between the piston and cylinder wall, which prevents pressurized combustion gases from entering the oil sump. They also regulate oil consumption by preventing excessive oil from entering the combustion chamber and burning. Properly functioning rings are vital to maximum engine power and efficiency.
Video transcript: How to Fight Piston-Ring and Cylinder Wear
Featuring John Gardner, ASE Master Certified technician, automotive technology instructor and host of Motorhead Garage, with AMSOIL Director of Product Marketing Len Groom.
John Gardner: Well drop the remote. You found the right show. This is Motorhead Garage presented by dragonfiretools.com. You know, Nicholas Otto invented the four-stroke cycle engine back in eighteen seventy-five, man.
That’s a long time ago, and it’s still around today. And let’s talk about the four-stroke cycle. Welcome to this AMSOIL Tech Tip. When it comes to the four-stroke cycle, well, there it is.
You can see the piston’s on its way down. That’s stroke number one called the intake stroke. The intake valve’s open and the air fuel mixture is being drawn into the cylinder. Then it’s on its way up.
Well, that’s the compression stroke. It’s squeezing that fuel. It’s getting ready to combust. Once it combusts, well, that’s the power stroke.
You see the third one over there? That’s when it actually happens. Bang. Pushes that piston down.
The piston’s moving down and then the last stroke gets on its way back up, and it’s on its way back up. That exhaust valve has to open, and when that opens, all the exhaust comes out of there. Now along with that four-stroke cycle, you have some wear issues that are going on. You see the first graphic right there?
We’re talking about forty-five hundred degrees inside of that cylinder, Fifteen hundred going to the outside coolant jackets and even more important, the ring wear. You can see that on the cylinder going up and down from the lower to the top there. You got a lot of ring wear and you could create a ridge.
Len from AMSOIL, buddy. This is a lot going on here. We have some rings, compression rings, but this oil ring right here, this supposed to scrape the cylinder and keep the oil from going up there. And if it’s doing its job, well, you’re not getting much lubrication, are you?
Len Groom: That’s exactly the the piston rings as we all know are about sealing and that oil ring is about scraping away any oil so you’re not burning it and putting it through the catalyst system and into the atmosphere. So if it’s doing its job, it gets dry up there and wear can happen. So one of the good ways to bring in some lubrication is in the fuel, and you can do that with a fuel additive. AMSOIL upper cylinder lubricant is designed just for that. So we’re gonna bring it in in the injector, and some of the chemistry that we’re using in this particular additive is designed to hold up to some of those extremely high temperatures that you mentioned earlier about combustion. So they’re going to stay around and they’re not going to burn off. They’re gonna help reduce some of that wear that you can see inside of these engines.
John Gardner: Now I can’t see as a customer, but it’s a good idea to put it in there because of the longevity of keeping my vehicle.
Len Groom: Correct. People are keeping their cars longer. You’re seeing more miles being put on these vehicles before they’re traded or sold off. So you need to maintain it because at the end of the day, you’re maintaining performance, you’re maintaining fuel economy.
John Gardner: Well, that’s huge. Go to their website, AMSOIL.com. Check out this product and so many more.
Let’s take a deeper dive.
What do piston rings do?
Most stock automotive pistons have three rings, as shown here on this new automotive piston.
The top and second rings are responsible for pressing tightly against the cylinder wall and sealing the combustion chamber, keeping combustion gases in and oil out.
The oil ring scrapes oil off the cylinder wall on the way down the cylinder, depositing it back into the oil sump. Because an extremely thin film of oil lubricates the ring/cylinder wall interface, it is normal for some oil to burn during combustion. What constitutes “normal” oil consumption, however, depends on the engine.
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Brad Nelson is an AMSOIL Technical Writer II who develops content about lubricant technology, product performance and vehicle maintenance. He works with engineers and product specialists to translate testing, application requirements and approved performance claims into clear customer guidance. Nelson’s work includes AMSOIL Blog articles, AMSOIL Magazine features and technical explanations concerning motor oils, gear lubricants, vehicle systems and maintenance practices.
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