AMSOIL Slip-Lock™ Differential AdditiveNow Available in an “Easy-to-Install” Tube

A universal additive that is suitable for any brand of car or truck limited-slip, locking or posi-trac differential. Effectively halts the incidence of differential noise. Compatible with any brand of conventional, semi-synthetic or synthetic gear lube. An ideal replacement for OEM limited-slip additive products.

Slip Lock package sizes include:
4-oz. Tube
4-oz. Tubes (case of 12)

When is AMSOIL Slip Lock Needed?

AMSOIL Slip Lock Differential Additive is needed during some gear oil changes performed on limited-slip (otherwise known as positraction or posi-trac) differentials or locking (also known as “locker”) differentials.

Some gear lubes may not have the proper frictional properties to allow limited slip clutches to actuate correctly and clutch chatter can occur.

In automatic locking differentials, the central driver (also known as spider gears) engages and disengages when wheel spin is sensed. A “clunking” noise can occur during this process if the gear lube does not have the proper frictional properties. Locking differentials are generally found in off-road vehicles these days.

To prevent or eliminate limited slip and locking differential noise, simply add a bottle of AMSOIL Slip Lock Differential Additive to your favorite gear lube.


AMSOIL Slip Lock Differential Additive can be used in any limited slip or locking differential that requires a friction modifier added to the gear oil. Slip Lock is a suitable substitute for any OEM or aftermarket friction modifier for differential use. Slip Lock is compatible with any brand of regular, synthetic-blend and full synthetic gear lube.

Some gear lubes are deemed as “limited slip compatible” and their labels state that limited-slip additives are not needed for proper performance. Slip Lock can be added to these types of gear oils to prevent or cure differential noise resulting from an imperfect frictional situation.

Do not use AMSOIL Slip Lock in automatic transmissions or any component that calls for automatic transmission fluid.

Installation Directions

  • Simply add AMSOIL Slip Lock Differential Additive during the differential oil change process.
  • Slip Lock can also be added to differentials after oil changes if differential noise is present.
  • After the installation of Slip Lock Additive, find an open parking lot and slowly drive the vehicle in figure-8 pattern for a few minutes. This process will burnish the friction modifier additive in the gears and clutches of your differential.

Is Slip Lock Needed with AMSOIL Gear Lubes?

AMSOIL Severe Gear and Long Life gear lubes are designed to function properly in limited-slip differentials without the use of friction modifier additives in most differentials. We have seen situations where some differential chatter can still occur with AMSOIL Gear Lubes, so we suggest adding about 2/3’s of a bottle of Slip Lock (just to be sure). As mentioned, this applies to any brand of gear lube. Learn more in our article Is Friction Modifier Additive Needed With AMSOIL Gear Lubes?