I have worked in a radiator shop for 10 years and want to give something back for all the great advice i have recieved here. car only heating when sitting for a short lenght of time (problem is no fan shroud , electric fan not operating properly , fan not operating properly or low coolant level. too test fan put a sheet of paper infront of radiator with car running fan should suck paper tight to radiator and hold it their.car over heats all the time? several causes but fairly easy to find. bad thermistat(car overheats top radiator hose never gets hot)collapsing bottom radiator hose(with car in park rev engine to about 3000 rpm note if bottom rad hose is collapsing due to no spring inside of hose( more common than most people would think)clogged radiator(only way to verify is remove radiator and take to rad shop to flow test .only takes a few minutes and you no if its a rad problem (havent seen many problems with aluminun rads) anybody having problems can pm me and I will be glad to give any advice thanks