since the mid 90s theyve used one shot grease stc3435 ,but it doesnt matter wich grease was only used so that they where filled for life instead of regular service item as with oil it doesnt lubricate better than oil but is less prone to leak ,the only way to check grease level is to strip swivel down and refil comes in measured sachet,its level can be reduced through leakage externally or into diff oil internally,often i refill or top up with oil if unsure of level ,easy on earlier housings as they have level plugs harder on later as they dont level for oil should be to top of steering arm so need something as dipstick ,mixing the two is okay,but dont overfill with both or either air space is needed in housing