What are the safe vehicle seat belt systems I can use with my Graco car seat?

Safe vehicle belt systems include: lap belts that are manually adjusted by pulling excess belt while pushing down on the restraint; lap belts with automatic locking retractor (ALR) that won't lengthen once buckled; combination lap/shoulder belts with a locking latch plate that won't allow the lap portion to loosen; and combination lap/shoulder belts with a sliding latch plate (which must be converted using the provided locking clip). You can also use LATCH in place of the vehicle belt system if your vehicle is equipped with LATCH anchor points.