A standard open differential uses spider gears that allow the left and right drive wheels to turn at different speeds freely (which is necessary when making turns), but this results in up to 100% of your power going to the wheel with the least traction. Limited-slip differentials (sometimes referred to as Positration or Traction-Lok differentials) dramatically improve traction by using clutches or gears that help to evenly distribute power to both wheels on your axle – in other words, no more embarrassing one-wheel burnouts! An air or electronic locking differential acts just like an open differential in normal operation, but can lock the left and right wheel together like a spool with the push of a button – making it preferable for heavy off-road use. A mechanical locking differential locks the left and right wheels together during normal, straight driving, but unlocks when making turns – allowing the wheels to spin at different speeds just like an open differential.
A limited-slip differential is often a factory option on rear-wheel drive based vehicles, though there's always room for improvement. By using a beefier clutch pack and stiffer clutch springs or a set of worm and spur gears, a high-performance limited-slip differential will hold the wheels together more tightly than an OE limited-slip. Generally, the clutches and gears will last the life of a vehicle as long as a few key guidelines are used. First, make sure to use the gear oil specified by the vehicle's manufacturer and if using an aftermarket differential, consult the instructions for the differential regarding the addition of a friction-modifier to ensure smooth, chatter-free operation. The other tip to ensuring your limited-slip will last is to not allow one wheel to spin freely. Mashing down the go-fast pedal when you're stuck in the mud or snow can allow one wheel to spin excessively and burn-up the clutches in the differential. Fortunately, the clutches can usually be replaced if needed.An air or electronic locking differential can provide better traction than a limited-slip, but only when locked – which should only be used on loose surfaces such as sand, mud, snow, and ice. This is what makes them ideal for hard off-road use.