Rear cargo door is slow to open on my 2016 Toyota Highlander. Can I grease the lift supports?

I would advise against adding lubrication to the lift supports. Doing so can actually leave behind residue that will collect dirt & debris which will ultimately be introduced into the lift supports, causing premature failure. If the supply voltage is sufficient, it could be that the supports need replaced, they've likely gotten weak and are struggling with the load of the door. If you have any other questions feel free to give us a call at (877) 913-1554 Dusty