Are driveshafts/ CV joints things that will wear out eventually even when the boots & grease around the bearing are intact?
Or do they only break down when the boots are torn and the grease thrown out while sand & dirt gets in?
If it is the latter, would it be prudent to replace those boots & grease while they are still intact when the car is say 4.5 y.o. and 100K km on the odo?