"While shopping at a major retailer, I came across a quart of SAE 30W oil with a service rating of SA," recalls Nelson. "After reading the back of the package, I chuckled as I discovered it's stated not to be used in any engine newer than 1930. Users need to ensure they're getting the right oil for their application. In most cases today, SL or SJ are the categories to stick with."
In addition to quality, the viscosity grade of the oil you choose is very important to engine performance because it refers to the oil's ability to flow. In warmer temperatures (anything over 40 degrees), you want to use a heavier oil (say, an SAE 30), because it's thicker and more viscous vs. a multi-grade oil like 5W-30 or 10W-30. This same oil, however, if used in the winter, will be too thick to easily coat engine parts and is also harder to start. So, in colder temperatures, it's necessary to use a thinner or multi-grade oil (5W-30 or 10W-30). Multi-grade oils don't thicken as much in colder temperatures and don't thin out as much in higher temperatures.
"In many instances, it's possible to use a multi-grade oil all year round," says Smith at Valvoline.
In some cases, synthetic lubricants can be a good choice for small gasoline engines because they perform well in any temperature range. The downside is they cost more, maybe as much as four times more for a quart.
Nelson notes for equipment that's used throughout the year, such as a generator or light tower, synthetic lubricants can be worth the extra cost because of the assurance they provide of proper lubrication and protection without the worries about keeping up with seasonal temperature changes.
While more flexible in varying temperatures, synthetic lubricants still require the same change intervals as organic, or mineral-based, oils.
"Most Honda General Purpose Engines recommend that the first oil change occurs at the 20- to 25-hour time frame and then about every 100 hours or once a year," says Joel Borowski, manager of technical operations for Honda Engines. "The oil should be changed more frequently in dusty or severe conditions."
He adds, "It's always recommended that the oil is changed when the engine is warm. This does two things: gets the contaminants that are in the engine suspended in the oil so they can be drained out and it allows for quicker and more complete oil drainage."
In between oil changes, it's a good idea to check the oil level frequently.
"I can't stress enough that rental businesses need to check the oil when a piece of equipment goes out and when it comes back in," says Nelson at Briggs & Stratton. "You need to make sure the oil is at the right level."
Borowski agrees, adding, "The rental business should ensure that the oil level is full when the customer takes the unit and that the customer knows how to check the level. The customer should know what oil is to be used in the engine if any oil needs to be added during the rental period. Oil weights should never be mixed in the engine. Using a different brand of oil is OK as long as it is the same weight."
While fuel producers do a good job of policing themselves in terms of meeting standards, there are things you can do to ensure the fuel you use is the highest quality and will provide the best performance.
Perhaps the most important point to remember with fuel is to use the freshest available.
"Fuel starts to degrade after about 30 days," says Nelson. "After that, the light ends of the fuel evaporate and when they're gone, all that's left are the heavy molecules. Then the fuel can't vaporize as easily. Fuel needs to vaporize because that's what actually makes it burn."
Old, stale fuel won't wreak havoc on engine parts the way low-quality oil will, but it will eventually gum up the carburetor, fuel line and fuel tank. Deposits build up, ultimately requiring parts to be replaced.
Less serious, but frustrating nonetheless is vapor lock, a phenomenon which occurs when fuel vaporizes too much, creating bubbles which clog the passageway to the carburetor jets, which then causes the engine to die. While not a permanent condition, vapor lock can frustrate a rental customer who rented a machine from you only to get it on the job and have the engine keep quitting.