1998 Buick Century Owner's Manual - Page 292

To check the aim, the vehicle should be properly prepared as follows: 0 0 Place the vehicle on a level pad or surface. The vehicle should not have any snow, ice or mud attached to it. The vehicle should be fully assembled and all other work stopped while headlamp aiming is being done. There should not be any cargo orloading of the vehicle, except it shouldhave a full tank of gas and one person or 160 lbs. (75 kg) on the driver's seat. Close all doors. Tires should be properly inflated. Rock the vehicle to stabilize the suspension. For the vertical adjustment, state inspection stations will generally allow a reading of plus 0.76 degrees or minus 0.76 degrees from the center of the bubble. It is recommended that the upper limit not exceed plus 0.4 degrees from the center of the bubble. Other drivers may flash their high beams at you if your adjustment is much above plus 0.4 degrees. 0 0 0 0 0 NOTICE: To make sure your headlamps are aimed properly, read all the instructions before beginning. Failure to follow these instructions could cause damageto headlamp parts. 6-32