Lubrication of a combustion engine is difficult due to the high temperatures and fluctuating high loads exerted. The lubricant chosen must perform several functions including the following:
1. Must have a suitable viscosity to carry heat from the engine.
2. Oiliness, to ensure adherence to the bearing for less friction and wear.
3. High film strength, to prevent metal-to-metal contact.
4. No tendency to corrode or attack engine components.
5. A low pour point to allow the flow of lubrication at low temperatures.
6. No tendency to form deposits when combined with combustion deposits.
7. Cleansing ability, to clean the deposits form the engine.
8. Dispersing ability, to break up and carry foreign material in the oil.
9. Nonfoaming characteristics, prevent the blending of air and oil.
10. Safety, nontoxic and nonflammable.
11. Low cost.
If the oil can meet the needs stated above satisfactorily, the chance of failures due to oil will be slim to none.
Before actually stating the minimum amount of oil needed to perform the lubrication task many things must be considered. First the engine is designed for racing and will be run at high output levels for a very short period of time (1-2 minutes). Secondly the oil that is used is a good quality racing oil that meets and exceeds the recommendations listed above. Last but not least the oil is changed after a short period of running. With all of these considerations taken into account, the minimum amount of oil that Briggs and Stratton Motorsports recommends is 11 ounces. Although some racers may run less than recommended, the risk of oil related failures become very high.