The engines in normal cars are designed for comfortable driving and have to last for a long time. This is why the power is spread over a range of RPMs (revolutions per minute) in order to acquire a linear acceleration. An engine in a race car has to endure a lot of stress. These engines are often tuned and designed to provide maximum power and torque at high RPMs. They produce extreme heat and pressure which would not occur in a normal car. This is obviously very demanding for the engine and therefore the oil should offer protection accordingly.
‘Regular’ engine oil is designed to clean, protect, and lubricate your engine over the course of 20.000 km. It has to have properties such as wear protection, a long oil life, maximum fuel economy, corrosion protection, and oxidation resistance. Race engine oil on the other hand is changed very often, after one or a couple of races. Engine oil oxidation doubles with every 10°C increase in oil temperature and in race cars temperatures are normally considerably higher than in street cars. Furthermore, because race engines endure high pressures and loads they need extra anti-wear protection. These are anti-wear additives such as ZDDP (Zinc Di-alkyl Di-thio Phosphates) which are particularly effective in the protection of the much higher stressed valve-camshaft train. Friction reducing additives like Molybdenum Di-alkyl Di-Thio Carbamates are often added in an effort to reduce the friction between all the moving engine parts. The normal amount of detergents and dispersants in an oil could compete against these additives that are so crucial for a race engine and you often see a reduction of these with subsequent lower TBN (Total Base Number) values.
The most common type of race oil is a 10W-60 viscosity grade based on a Group IV full-synthetic PAO base oil blend. However, there are many base oil mixtures possible. An important specification of racing oil is a HTHS Viscosity Requirement (High Temperature/High Shear) of a minimum of 3.7 mPas, which indicates a higher load carrying capacity of the oil than normally seen in API or ACEA defined specifications where the highest requirement is a minimum of 3.5 mPas.
Like race cars are designed with a different purpose in mind than normal cars, the same applies to engine oil. Race engine oils are designed to meet the requirements of race cars and therefore have different properties than regular engine oils.