A person can find out the oil capacity of a vehicle by checking the owner's manual, looking at the manufacturer's website, looking at a specialty website or using the oil dipstick. One can also pay a mechanic to change a car's oil, but this is typically a more expensive route.
When checking the owner's manual, the section titled "Vehicle Specifications," or something similar, should contain information on a car's oil capacity. This section should list information on oil capacity with and without a filter, and in units of quarts.
If a person lost or does not have an owner's manual, he should visit the manufacturer's website in order to find out a car's oil capacity. Most manufacturers' websites feature online owner's manuals and technical information sheets for vehicles they sell.
In case a manufacturer's website does not contain information on a specific vehicle, a person can check a specialty website such as fluidcapacity.com. On this site, click on the Fluid Capacity Lookup tab and then the Online Product Application Guide button. After typing in a vehicle year, click "Build List" and the site will produce a list of auto models and manufacturers along with oil capacities and the types of fluids each model needs.
If using a dipstick to figure out a car's oil capacity, insert the dipstick where appropriate and then pull it back out. The oil clinging to the stick will show how close a car is to the top of its range.