Can someone please explain what putting oil in the diff gives you and what the affect of different weights is? (or direct me to an online article that explains)

oil or grease in the diffs limits the slippage of the differentials. the heavy weight is less slip which means more power to the wheels. less weight gives you more slip and allows the wheels to spin more freely on slippier surfaces. heavier wieght is kinda like a diff locker. hope thsi helps.

As the diff oil gets heavier, both tires (Left and right) on an axle will spin closer to the same speed. If you are wanting maximum traction in straight line, go with super heavy diff oil - Say 100k. If you run 100k on pavment, your LST will turn like a bus - i.e. it will push the front end instead of turning sharp. If you want a very small turning radius on a high-traction pavement, go with a very light oil - The light oil allows the outside tire to spin faster than the inside tire (Hence the "differential" action). I run 30,000 (30K) oil in both Front and rear and have a respectable turning radius, as well as lots of traction...30K is a good mix of both worlds. I run both on and off road and really like the way the 30K performs.

While you are at it, get a Losi swaybar kit (You only need 1). They make a big difference and keep your LST cornering flat for maximum tire contact.

Thanks guys, this helps a lot. I am going to give it a try.