Pretty simple.... we don't want your engine to seize or transmission to fail or vehicle to overheat when in the body shop. A good shop makes sure that all your chem are topped off and battery is fully charged.
I had a very very slow leak from main rear seal on Forte with a couple of drops a day and tried a few diff HM oils as well as a few Stop Leak additives to no effect. Then I tried Castrol HM 10w-30 and it did the trick. Hope it stays that way. Not a fan of Castrol as a brand thou they do make good oils.