Yeah, it's usually just the seal at the top of the lowers.
Do keep in mind that you need to remove the lowers to replace the seal, which means you'll need to drain whatever oil is left in the lowers. So make sure you have a large enough plastic tub and also have the correct amount and type of oil on hand.
Get a syringe (no needle needed, just the syringe itself) of the correct or a slightly larger capacity than what you need to put in each leg. That'll make putting the new oil in the lowers much easier.