Everyone knows that oil lubricates things inside an engine. But it does a lot more than that. And here to give us some tips: Lyndon Abel, General Manager of Patriot Harley-Davidson in Fairfax, Virginia. Lyndon, welcome back to the show.

LYNDON ABEL: Thanks for having me, Pat.

PAT GOSS: Alright. Oil lubricates, but does a lot more.

LYNDON: Absolutely. It does four things. Everybody knows it lubricates. It also cleans, prevents corrosion, and it cools. And a lot of people don’t think about this. But oil is a very important part of the cooling of any engine, especially so with an air-cooled engine. But really any engine. That oil is circulating near the combustion chamber, carrying a lot of that heat that’s generated by combustion, back into an oil tank where it can syphon through and dissipate some of that heat into the atmosphere. Dirty oil simply doesn’t do that nearly as effectively as clean oil.

PAT GOSS: Alright, so if we take our dirty sample here, and we shake it, we can see that there’s all kinds of crud floating around in there.

LYNDON: Right, and that crud is specifically interfering with cooling off your motor. That doesn’t do anything to help cool things off, and it slows down flow and interferes with that cooling. So yet another reason to keep the oil fresh in your motor.  Change the oil regularly. And use the proper oil, and that will go a long way in helping keep things cool.

PAT GOSS: Speaking of proper oil: one of the reasons for the proper type and viscosity and everything, is to keep it flowing at the right rate so that it can absorb enough heat and dissipate enough heat.

LYNDON: Absolutely correct. And different motors are designed for different viscosity oils.

PAT GOSS: Alright, the outside is critical as well.

LYNDON: Right, so here we have a Harley-Davidson cylinder and cylinder head. And this is air-cooled of course. And these fins, the job of these fins, is to absorb the heat that’s being given off by friction and to a much greater extent, combustion. And then that heat travels on this aluminum fin out into the air, where that heat is then pulled out by the wind that’s going past the motor. This works great until these fins get clogged up with dirt, bugs, road grime and debris. So don’t ignore the motor when you’re cleaning your motorcycle. Be sure to keep all of these things cleaned in order to properly cool the  outside of your motor as well. 

PAT GOSS: Ok. Lyndon, thank you. And remember folks, clean on the outside of a car engine is important too, because it has a big effect on how cool the engine runs. And if you have a question or a comment, drop me a line, right here, at MotorWeek.