Automotive Vs. Motor oil: the differences explained – Jalopnik

Before you even think about pouring automotive oil into your motorcycle engine, get your facts straight. Not all oils are created equal, and automotive motor oils have advanced to the point where some engines require manufacturer-specific oils to function properly without voiding the warranty. Not long ago, motorcycle engines were compatible with automotive engine oils, but oils had to evolve to meet burgeoning emissions standards.

That meant that automotive engine oils began to contain friction modifiers to better protect against cold starts while improving fuel economy. In case you’re wondering, friction modifiers are anti-wear additives that help reduce friction and metal-to-metal contact. They contain chemical compounds that bond to metal surfaces, such as the fibers of a carpet, and protect the underlying metal from light friction.

Friction modifiers are especially useful during cold starts, when almost all the oil has been drained to the crankcase, because they provide a thin barrier of protection for cams, bearings and pistons. However, the same friction modifiers and other additives in automotive oils are incompatible with motorcycle engines and in some cases can cause drivetrain and clutch problems, which are systems that rely on some degree of friction to work effectively.

For starters, many sport bikes can rev up to 10,000 rpm, while some performance bikes have screaming engines that can rev up to 20,000 rpm. Compare that to your gas or diesel truck, and the numbers aren’t even close: Most car engines have red lines at 6,000 to 7,000 rpm.

The point is that higher RPMs put enormous strain on the engine and its internal components. Motorcycle engines are exposed to extreme heat, higher loads and twisting and sliding, which can degrade the lesser engine oils. The extreme twisting and shearing can also cause incompatible oils to foam, further impairing lubrication and causing increased wear. And when the oil deteriorates or starts to foam, something goes wrong; This can damage the engine of your bicycle.

On the other hand, a Harley Milwaukee-Eight 107 engine can see rear cylinder temperatures exceeding 420°F while rhythmically vibrating and burrowing premium gas (at least for newer models). The point is that motorcycle engines run hotter than car engines, so why should we use oils designed for cars? You could argue that the best synthetic car oils can also withstand intense heat, but not to 400 degrees or more.

At that temperature, lesser oils can easily lose their viscosity, and extreme heat can oxidize or break them down more quickly, meaning you’ll need to replace them more often to get a consistent level of protection. Motor oils are formulated to withstand higher temperatures than automotive oils. That alone should keep you from trying your luck with incompatible oils.

As a result, the engine is put under more strain, putting greater strain on its internal components. These conditions also stress the oil itself, which is where specialty motorcycle engine oils come into the picture. Motor oils are available in conventional formulas, synthetic blends and fully synthetic formulas and are designed to withstand higher temperatures while maintaining protection of metal parts.

Add to that the fact that motorcycle engines have smaller crankcases, which means less oil circulating. If you use car oil instead of motor oil, the extreme heat cycles and low quantity will eventually render the oil ineffective, leaving engine parts underprotected.

The friction improvers in automotive motor oils will not survive the extreme crushing, shearing and chipping of transmission gears, which also means they will wear out long before the real action begins. In addition, engine oils must be compatible with clutches that produce dust, while still providing sufficient lubrication to reduce wear. To handle this task, motor oils contain higher levels of chemical dispersants that trap dirt and keep the oil clean.

Therefore, engine oils must meet the quality requirements of the Japanese Automotive Standards Organization (JASO). JASO standards apply to two-stroke and four-stroke engines, with oils that have an MA, MA1 or MA2 label on the packaging. You can find out which JASO classified oil is suitable for your motorcycle in the owner’s manual. As a general rule, synthetic oils provide the highest level of protection, but also come at a higher cost. It is always best to stick to the recommended viscosity grade unless you are using a modified engine.