A chainsaw relies on lubrication to maintain performance. Without the correct oil, the tool will experience rapid wear, excessive heat generation, and potential mechanical failure. The high-speed components of a chainsaw, from the internal engine parts to the external cutting mechanism, demand specific lubricants to manage the friction and heat they generate. Using the wrong type of oil or neglecting the lubrication schedule can quickly lead to costly damage and a shortened tool lifespan.
The Two Essential Lubrication Systems
A chainsaw requires two entirely separate lubrication systems, each with its own dedicated oil reservoir and function. The first system lubricates the internal engine components, such as the piston, cylinder, and crankshaft. This oil is consumed during the engine’s operation and is not recirculated.
The second system lubricates the external cutting apparatus, specifically the guide bar and the saw chain. These two systems use completely different types of oil that cannot be interchanged. Engine oil is designed to burn cleanly with the fuel, while bar and chain oil is formulated to cling to metal surfaces and is continuously expelled.
Engine Oil: Selection and Fuel Mixing Ratios
The majority of gas-powered chainsaws utilize a two-stroke engine, requiring the engine oil to be mixed directly with the gasoline. This process is necessary because the two-stroke design lacks a separate oil sump and relies on the fuel mixture for lubrication. The oil must be a high-quality, certified two-stroke oil, typically meeting the TC or TC-W3 classification, which indicates it is formulated to burn with minimal ash and carbon deposits.
The mixing ratio is specified by the manufacturer, often 50:1 or 40:1 for modern equipment. A 50:1 ratio means 50 parts gasoline to one part oil. Using too little oil causes the engine to overheat and seize due to insufficient lubrication. Conversely, using too much oil leads to excessive smoke, carbon buildup on the piston and spark plug, and poor performance. Less common four-stroke chainsaws, which are typically larger, use a separate oil reservoir and require standard four-stroke engine oil, similar to that used in cars, and do not require fuel mixing.
Bar and Chain Oil: Specialized Properties and Substitutes
The oil used for the cutting mechanism is called bar and chain oil. It is specifically engineered to handle the unique demands of the high-speed chain and guide bar. This oil is characterized by high viscosity and the inclusion of specialized polymer additives known as “tackifiers.” These tackifiers give the oil a sticky, cohesive quality, allowing it to adhere to the chain as it travels at speeds that can exceed 60 miles per hour.
The tackiness is necessary to prevent the oil from being immediately flung off the chain by centrifugal force, ensuring continuous lubrication and minimizing wear on the bar groove and chain links. Standard motor oil is strongly discouraged as a substitute because it lacks these tackifiers and is generally too thin, resulting in excessive sling-off and inadequate lubrication. While new motor oil may be used in a rare emergency to prevent running the saw dry, it will shorten the life of the bar and chain significantly. Specialized bar oils are available in different viscosity grades, with thinner options for cold winter temperatures and thicker oils for hot summer conditions.