Service Intervals and Exceptions to the Minimal Recommendations

While attending the Yamaha University course on V-Block Engines, Power Implements learned invaluable information pertaining to the maintenance of these great engines. Though today’s engines are filled with wonderful advancements in technology and performance, they are not impervious to damages. While this topic of discussion was spurred by information obtained from Yamaha’s course of study, it is directly related to all outboard engines currently in production. 

Outboard engine manufacturers have worked tirelessly to bring us advances in the technology and performance of today’s four stroke engines.  Another advancement that is often overlooked is research and development into improved maintenance products and lubricants. The cooling water for outboard engines comes directly from the body of water the boat is floating in.  Because the engines use this “raw water” for cooling supply, and that water is subject to minerals, salt, and various other deposits, the thermostats selected for use are of a much lower temperature than those for automotive use. Somewhere near 162 degrees Fahrenheit, these suspended materials begin to solidify in the cooling passageways of the engine block. The engine then begins to run hotter and unsafe temperatures. An unfortunate byproduct of running a cooler thermostat is the build of carbon deposits in the combustion chamber of the engines. The thermostats aren’t the only concern that leads to carbon build up, and we will learn more about each of the other concerns in another discussion. For now, we will simply name a few of the other concerns. The quality and age of fuel being consumed, the high engine RPM’s our motors turn, hot oil being returned to an oil sump below the water line, and advances in on board electronics.

I know the last one sounds odd in relation to the service interval of an outboard engine, but let’s expand on this one a little more. At the same time engine advancements into four stroke technologies were occurring, big changes were made in the area of chartplotters and fish finders. With these improvements in design, our engines often run extended periods of time at idle speeds or just above it, while we enjoy beautifully detailed views of the lake or sea bed below and to the sides of our vessels. A couple of results of extended idling are cooler cylinder temperatures and consequently incomplete burning of fuel in the cylinder. Additionally, with regards to these accessory advancements, we are now encouraged, having found great opportunities to catch fish more consistently, to make longer runs with the boat. Though the engines are capable of remarkable reliability for extended periods of run time, we often fall into the realm of idling while graphing, and running wide open for long hauls. Following long hauls, knowing our marked points, arrive at our next waypoint, and abruptly shut down. This cycle leads to carbon deposits as well as fuel dilution.

Each manufacturer has slightly different recommendations on maintenance, but most seem to adhere to something along the lines of once a calendar year, or every 100 hours of usage, whichever occurs first. While this is a good place to start, it isn’t the only allowable interval. In fact, to maintain the best health of your product, intervals may even be as short as every 20-30 hours or once a year. For instance, the service interval on a pickup truck driven as a commuter on the highway will be greatly different than one that is used on a construction or farm site. 

Engine oil serves two primary functions. The primary function of engine oil is to lubricate the moving pieces on the inside of your engine. Another very important function of the correct blend of marine outboard engine oil is to clean the deposits left inside the engine. When these deposits are cleaned from the combustion chamber, and as a result end up in the oil pan, those deposits begin to break down and become corrosive. Another common question we hear is regarding an engine that has only been used a few times in one year. Should the fluids still be serviced, as the motor might have far less than the minimum suggested 100 hours? Absolutely. Those deposits becoming corrosive can cause harm to the oil pan as well as internal components even if the oil looks clean on the dipstick. As a dealer, we try the best we can to help our consumers understand these effects and recommend each customer working with their dealer to craft a unique and specific service interval to each application that best caters to the way each boat is used. And, only use manufacturer recommended products that meet the specifications for each product.