1 Why you need to oil your bike

Squeaks mean parts rubbing metal to metal, grinding and wear. Wear is bad. Corrosion and rust will ruin your bike over time as well as making it aesthetically poorer. Just because you can afford to buy a new bike is not a reason to let your current bike deteriorate to the point of being non-functional. Maintaining your bike will save you money plus will save the environment from the impact of producing a new bike. Maintaining the bike will save you from repairs and the cost of parts. Consider the cost of using sustainable vegetable oil over the maximum serviceable life of your bike compared to the cost of new parts or a new bike or bikes. The vegetable oil is much cheaper. One bottle of vegetable oil may save you several new bikes.
[edit] 2 Advantages

Using Vegetable oil to lubricate Bicycles has several advantages:

Vegetable oil is non-toxic. Working with vegetable oil eliminates the hazard of Toxicity. Typically repairing and maintaining machinery will cause the user to be exposed to liquid and atomised vapour of the lubricant. Oil will soak into the skin, especially on the hands where it will be ingested and vapour will carry on the air to the eyes, mouth, nose and consequently the digestive and respiratory system. Vegetable oil does not need to be kept out of reach of children.
Vegetable oil is non-carcinogenic. Avoid any Genetically Modified products. Many Organic and bio-dynamic products are available.
Vegetable oil is Biodegradable. Oil that is outside a sealed unit is called total loss oil, that is it finds its way from the exposed mechanical component and into the Environment. Oil that is put on a bicycle chain will end up evaporating to some extent and the rest falls onto the road, washes with the rain into our stormwater drains and into our creeks, Rivers and Oceans.
Vegetable oil is cheap. Pressurised aerosol tins of oil are expensive compared to liquid vegetable oil in bottles. To aid application you can fill a traditional oil can or use a pump spray atomiser bottle. An old laundry stain remover bottle can work fine or get a generic trigger spray bottle (such as those used for dampening your ironing). Mineral oil is incompatible with a variety of plastic components but vegetable oil will not dissolve or degrade plastics.
Vegetable oil smells nice. There is no nasty Chemical smell and you can even add a few drops of essential oil to make your bike smell of lavender or rose geranium for example.
Vegetable oil is soft on your hands. Mineral oils dry the skin and add to damage caused by doing mechanical work. Vegetable oil will nourish and moisten your skin. Your hands will be easier to clean after working with vegetable oil compared to working with mineral oils.
Vegetable oil can lubricate and degrease. Vegetable oil mixes with mineral oils and has the effect of diluting existing oil and grease taking away dirt and grit with it. Citrus oils are very light and viscous and very effective at dissolving mineral oil and grease.

[edit] 3 Some applications

Lubricate nuts, bolts, screws, internal and external threads. Vegetable oil can help free a seized nut, bolt or component like mineral penetrating oil would.
Lubricate cables for brakes, hub gears (like Sturmy Archer and Shimano) and derailleurs. This helps the cable move freely in the cable casing or outer plus keeps corrosion at bay.
Lubricate pivot points for brake callipers and levers.
Lubricate chain and sprockets.
Lubricate derailleurs.
Prevent rust and corrosion. Applying vegetable oil to the chrome and unpainted steel components of your bike will prevent rust. It makes the bike easier to service and undo nuts, bolts and screws when needed. Vegetable oil will also soften rust on chrome and steel and make it easier to remove the unsightly brown rust. Rust on the braking surface of chrome rims will have an abrasive effect on rubber brake blocks. Rims with surface rust can eat a set of rubber brake blocks within a week of regular bike riding.
Clean your chain and sprockets. Dirt, road grit and the detritus of wear will accumulate on your chain and sprockets. Apart from clogging the operation and interfering with smooth and proper performance, the dirty grease will wear the components like grinding paste.
Clean and polish paintwork. Dissolves the stains and leaves the bike shiny.
Clean and polish vinyl seats. Remove dirt and stains from the seat and leave it shiny and new looking.
Thread fixative: Dip ends of spokes into linseed oil (flaxseed oil) to coat screw-threads before screwing spokes into spoke nipples. When linseed oil dries, it keeps spokes from loosening, but allows for adjustment if necessary.