Tell them to use the parking brake
Owners of some GM vehicles (2009 and prior passenger cars and light trucks, including Saturn) with Hydra-Matic front wheel drive transmissions may comment about a grinding and/or growling noise when standing in Park on a hill or slope with the engine running and the parking brake not applied.
Under these conditions, the weight of the vehicle puts a load on the parking pawl which can create a “ground out” path through the drive axles, front struts, springs and spring towers.
Normal engine noise can be transmitted to the passenger compartment through the “ground-out” path. Owners should be advised to apply the parking brake prior to shifting into the Park position.
Applying the parking brake first will put a load on the vehicle on the rear brakes instead of the parking pawl.