I'm a firm believer in preventative maintenance and changing out fluids. I never used to change out transmission fluid myself personally. Then I started to do few pan drops and saw just how much magnetic shavings was on the magnets and how dirty the filter/strainer could be. It's also relatively easy to do as well. Fresh fluid is good for your transmission/engine/differential/transfer case/radiator/ brake fluid and power steering. I was @ my Nissan dealer just a few days ago getting a state inspection and free oil change. Spoke w/a really knowledgeable young service writer. First he asked why I brought in my own oil, Eneos 0w-20 when he says they use Mobil 1 0w-20 in bulk. Well, both are really good oils but, I didn't want to offend him by saying I'm not so sure they really use Mobil 1 0w-20. He stated be sure to change out the transmission fluid @ 60K mi. I told him I'll be doing this way before 60k mi. (probably around 20K mi.) as I like to get the break-in fluid out sooner than later. Easy to do. Use NS-3 Nissan fluid. The pan has a drain plug. Filling is easy. Put in what you take out. (As long as the factory put in the correct amount.) Later on after warranty is up, a pan drop. (I found out you can order a factory transmission dip stick for this engine which was used in another model.) Now onto your cooler question. He said the previous generation of CVT's didn't have a cooler to lower the transmission fluid temp. Along with not changing out the fluid, lots of issues/breakdowns. Our transmission is the latest version. Transmission cooler. Also other improvements as well. Excellent! These Rogue Sports should last a very long time w/timely maintenance. Ours is a FWD model. Nissan isn't the only manufacturer that has the same issues w/their 4 wheel drive models. I would have thought a larger diameter donut have been inc. w/17" rims. (What about the 19" rims?) Maybe this spare donut is made for the 16" steel wheel and used exclusively for all rim diameters? Do not know...I'll ask next time I'm @ dealer. (next yr. though hopefully.) Nothing to worry about (I do believe) but do ask your dealer about your transmission if you have any doubts. Hope this helps, Bill.