How do I choose the correct viscosity for my application? There are many factors to consider, some being engine design factors and some being operating factors. However, a lower viscosity oil has the potential to reduce internal power losses and improve power outputs. But the thinner film thickness with a low viscosity oil may result in higher wear rates and demands improved surface finishes and tighter tolerances. Additionally, a low viscosity oil may suffer from higher evaporation and consumption rates while having a reduced ability to handle fuel dilution.

Turbocharged applications will usually require a higher viscosity oil due to the additional heat loads and the very high power densities. Obviously the bearing clearances, oil pump flow rates, and oil cooling methods should all be adjusted together with the oil viscosity to suit the specific application. Street driven applications will clearly have much different requirements than racing applications.

Can you explain what the oil viscosity rating means where there are two numbers used? Multigrade oils will be designated as two numbers separated by a "W". The first number indicates the viscosity of the oil under cold conditions (0°F) while the second number indicates the viscosity under hot conditions (212°F). A lower cold viscosity will be necessary for the oil to begin flowing quickly on startup with tight oil clearances or under extreme cold conditions.

How often should the engine oil be changed? Use the manufacturer's recommendations. Heavily modified vehicles should always follow the severe duty schedule. If desired, use an oil analysis company to help determine whether you can extend the interval or if the oil should in fact be changed sooner. For motorsport applications change the oil after each event.

What is the difference between Motul 8100 and 300V? Both oils are 100% ester type synthetic oils. However, Motul 8100 is formulated to meet manufacturer requirements for road use. Its formulation and additive package are fully compatible with emissions devices and achieve the desired level of protection, fuel economy, and resistance to sludge formation for a wide range of drive cycle types. On the other hand Motul 300V is engineered for motorsports applications and is designed to provide the best possible performance in a motorsport environment and the most extreme conditions and temperatures. It uses the latest advancements in technology including Motul's new Ester Core technology.