Many engine manufacturers today keep the rental industry foremost in mind when designing commercial engines. when designing engines, manufacturers need to consider the products' specific needs, such as larger capacity, or cyclone air cleaners for concrete saws, or low-tone mufflers on generators.

Engine makers also understand that equipment downtime is the biggest profit drain in the rental business and try to design engines that allow quick and easy maintenance. For example, engines with two oil-fill and two oil-drain locations on opposite sides with easy access to spark plugs facilitate service. Oil alert systems have eliminated most of the frequent and costly causes of downtime.

Here are tips that can help you better service the engines in your rental fleet. Although different brands of engines have similarities, maintenance intervals might vary. Always check your owners' manual before determining maintenance schedules.

* Always use 10w-30 motor oil with an SJ classification, except during extreme hot or cold weather. Engines run cooler when 10w-30oil is in the crankcase.

* For longer spark plug life, set the ignition coil gap at 0.20 mm. That puts the coil closer to the magnet, so the plug will get higher voltage out of the coil every time the engine starts. As a plug wears, more voltage is required before it sparks. If higher voltage is available, that line has to go higher before it starts sparking. Voltage requirement for inducing spark at the plug increases as the plug wears. If you make the air gap tighter, it can spark the plug longer.

* Use an hour meter to remind you of scheduled maintenance. The hour meter should be placed unobtrusively so the customer is less likely to tamper with it or attempt to shut it off.

* The recommended oil change interval is 100 hours. Perform a general tuneup and change the spark plugs every 300 hours. Check the clearing on valve settings about every 300 hours.

* Check the air cleaners as needed. If a machine is being operated in a dusty environment, or is a machine that creates a lot of dust such as a concrete saw, check the air cleaners more frequently. Make sure excessive dust is not altering the fuel mixture on the engine, making it hard to start.

* If you have seasonal equipment and store a unit for more than a month, always use a fuel stabilizer to keep the fuel from going stale. Stale fuel can make the engine difficult to start.

Create responsible customers Rental personnel also should train their customers to perform preventive maintenance such as the following:

* Checking the air filter every time they fill the gas tank.

* Shutting off the gas when they shut off the engine.

Rental companies should partner with their customers to improve the products' performance. As a manufacturer, we believe in trying to exceed the expectations of customers. If rental companies treat their customers the same way, those customers will keep coming back for more.