If you're an average rider, an all-purpose lubricating oil designed for bikes will be all that you need. You can use oil to lubricate pivot points such as brakes and derailleurs, as well as to keep the chain lubed.
Some riders use a lubrication specially designed for a chain. Manufacturers offer a number of quality lubes that are designed with different conditions in mind. A dry wax-based lube is best for dry, summer-like conditions. For the rainy season, a wet lube is the choice for many riders — although a wet lube is messy and attracts dirt and grime, it holds up well to water.
Liquid lubricants can be applied from an aerosol can or a plastic squeeze bottle. We prefer to drip a lubricant out of a bottle because we can control the flow. Spray cans are much more difficult to control and can overlubricate parts.
When you need to loosen a seized part — such as a seat post that won't budge — use a light, penetrating oil like WD-40.
WD-40 should not be used as a chain lubricant. Although WD-40 works wonders in getting tight parts moving again, it's a solvent that will strip away existing lubrication. Although it may appear to be lubricating while it's wet, as soon as it evaporates, your chain lubrication will be gone. Also keep WD-40 away from shifters, because it may damage the inner parts.
In addition to oil, grease is needed to support the internal moving parts of your bike, particularly those that depend on bearings to reduce friction. Bearings in the hubs, bottom brackets, headsets, and pedals are packed in grease. When these are overhauled, the grease needs to be replaced. Grease also protects the threads found on the same parts and lubricates and prevents rust from forming on the gear and brake inner wires.
Grease is often sold in a tube. Be sure to keep the lid on at all times to prevent contamination.Buy only grease designed for bikes. Grease for automobile bearings will be too heavy and thick and will gum up your bike.