Through the World War II era, most motor oils were of a single weight makeup. The first number, e.g., 10, is an SAE numeric representation of the oil's viscosity. Oil viscosities are typically measured at SAE 5, 10, 20, 30, 40, 50, and 80 weights, with the smaller numbers representing low viscosity/thinner oil. Therefore, 10, in SAE oil terms, represents a grade of oil that is fairly thin, with the ability to lubricate quickly at cold temperatures. The SAE rule for measuring different viscosities is taken at 40 and 100 degrees C (or 104 and 212 degrees F, respectively).
Behind the first SAE numeric representation is the letter W. This symbol stands for Winter Grade with relation to a range of temperatures the oil is capable of operating within. A 10W designation informs the user of the oil's viscosity with relation to low operating temperatures in accordance with an SAE 10-weight scale that can be measured at 40 and 100 degrees C.
As for the SAE 30 designation, in our 10W-30 example, this addition is a blend of induced polymers injected into the original base oil to thicken at high temperatures. The blended oil will then take advantage of the low-viscosity rating of an SAE 10-weight oil at lower temperatures and cold starts while also having the ability to withstand harsh environments at high temperatures without breaking down. The polymers used in the '50s did not last very long and broke down quickly, reducing a multigrade oil back to its single-weight makeup. However, today's multigrade oils feature highly advanced polymers capable of lasting the entire duration between recommended oil changes.
Conventional-base motor oils should operate within an approximate temperature range of 180-200 degrees F. Synthetic blends offer better performance at low temperatures, and their makeup allows them to handle slightly higher temperatures, offering a safe range of approximately 160-250 degrees F. As engine oil exceeds these temperature ranges, it begins to break down faster. This does not mean a sustained oil temperature of 300 degrees with a synthetic oil will cause an engine to lock up due to failing oil. Today's motor oils are superior to today's metals. However, dramatically increased oil temperatures will require more frequent changes.
Synthetic oil typically lasts longer because it has a more highly refined base stock combined with a stronger and better additive package that can handle a wider range of temperatures and the abuse that comes from operating in a performance environment. Conventional oils will break down faster and should be changed more frequently (see manufacturer's recommendations). Beyond lubrication, oil also has the job of cleaning the engine internally. This means that debris needs to be taken to the filter, and acidic combustion contaminants must be trapped.
Before storing a vehicle, the oil and filter should be replaced. This will help rid the engine of harmful substances, such as acids, that could potentially break down the oil during storage. Conventional petroleum-base oils will typically adhere to a resting internal component for anywhere from 6-8 weeks, whereas a synthetic-base oil is more likely to coat the engine internals for 3-6 months. After long periods of storage, it is a good idea to pull the coil wire from the engine and use the battery to crank the oil pump and prime the engine. With the oil basics covered, we can move on to the internal hard parts of an engine.
Road racing? Drag racing? Get the right pan and ensure you have an adequate supply of oil and pressure. | 
Upon close inspection of this high-performance Canton oil pan, we can see the built-in windage screen at the bottom and the side-mounted crankshaft-scraping rails. |