Replacing all four motor mounts is not always necessary. If one or two of your motor mounts are in good condition, you can keep them and just replace the ones that are worn out. Here are some factors to consider when deciding whether to replace all four:
* Check for signs of wear or damage on each mount.
* Consider the age and mileage of your vehicle - if it's older and has high miles, replacing all four may be a good idea.
* Ask an automotive expert for their opinion on the best course of action for your particular vehicle.