Q: strut is leaking on one side of the car.

Hi there. If a strut is leaking, then the strut tower that contains the oil for the shock absorber has a seal that split or got damaged. When replacing the shocks or struts, it is recommend to replace them in a pair. If you are planning on putting in new springs, then I recommend replacing both, but if you are not putting in new springs, then you only have to change the leaking strut. It is recommend to change both struts so you will not have to replace the other strut at an early interval. After replacing the strut(s), I recommend getting a vehicle alignment to prevent uneven tire wear. If you need further assistance with your strut(s) replacement, then seek out a professional, such as one from Your Mechanic, to help you.