Do I need to replace on 1998 Mercedes-Benz E300

when I took my car to change to snow tires, I was told that I needed to replace R Pinion Shaft Seal (rear both). How can I know I really need that and can you explain what it is.
Thank you!

Asked by for the 1998 Mercedes-Benz E300
The rack and pinion seal is at the top of the steering rack where the steering column or steering wheel input is transferred to the steering of your car. If the seal is leaking the power steering fluid level will drop and require frequent topping up. Ask the repair shop is is leaking or just weeping and how critical is it that this be replaced or repaired right now, ask them do they think it would "leak" requiring topping up every day , month, few weeks?