It's like $30 a bottle from GM. You'll need two bottles- one for each headlight. Remove the head light and pull all the bulbs out. Fill the housing with the fluid. Be careful putting the bulbs back in. If you spill the fluid, you'll have to buy another $30 bottle. The fluid acts sort of like dielectric grease, insulating the bulbs and preventing them from overheating and shorting out. It also helps to refract and focus the light properly for optimum light distribution. Without it not only will your lights look dim, but the bulbs will burn out a lot sooner too.