My 2008 Nissan Dualis ST 4x4 automatic transmission sounds like a chainsaw

This sounds awfully like badly worn transmission. The Dualis in automatic form used what’s called a CVT. Instead of gears inside the transmission, the CVT has pulleys and metal belts that vary their relationship and, therefore, create the various 'gear ratios' the car needs.

When these pulleys and belts wear, they can start to make the noise you’re reporting. And, just like your car, it will get noisier as time passes. Unfortunately, you’re probably looking at a transmission overhaul or rebuild. If you continue to drive it as it is, you’ll almost certainly do more damage, although it sounds like the real damage is already done.

Take the car to a transmission specialist who will be able to accurately diagnose the noise and take it from there.