can I put a transmission coolant on a 2010 Nissan sentra

It already has one, from factory, but if you want an aux. cooler here is a suggestion: Call 800-298-8924..they will fix you up. But you really don't need one unless you pull a trailer, or have your 300 lb Mother-in-Law, and 3 football players ij the back seat with 300lbs of gear in the trunk and are driving through Nevada in summer. But your car, your call. Not trying to talk you out of it...keep on keepin' on --Best Wishes

I pull a small camper so yes I need one put on my car. The factory one is no use at all.

Remember the Sentra maximum towing capacity is 1000lbs. It is not only limited by the transmission, but also by the brake capacity and the car frame. The engine is not that powerful also. Verify your numbers. It could be less expensive to buy something more rebust. It could happen if your car breaks.