Should you use copper grease?

While many mechanics and Diyers have used copper grease/copper slip for years, it seems to be falling out of favour. Were we all misguided?

DRIV told CM that its use is subjective and there are alternative greases available that are preferable for use on modern cars with ABS and traction control systems. Delphi and TMD Friction (Mintex) agree, warning that using copper slip, on newer vehicles especially, can prevent the anti-noise shim from working correctly – noise levels can increase, which are amplified by the surrounding brake and suspension components. As copper grease is mineral-based, it can damage rubber components, such as caliper piston gaiters. It is also not a lubricant but an anti-seize compound, meaning that it is unsuitable for applying to pad and caliper mounting areas. Surprisingly, it cannot withstand high temperatures, so it can hinder the pads from moving smoothly. Its copper content can also react with steel and aluminium, encouraging corrosion. As copper is conductive, its presence can cause electromagnetic interference with wheel speed sensors. When used between the hub and brake disc, it can increase run-out, which heightens judder and might lead you to blame the brake disc. Should you have access to a dial test indicator gauge (DTI), the maximum run-out measured on the hub should be 0.07mm. Note that worn/damaged wheel bearings also increase the risk of judder.

Considering copper grease’s limitations, you should use a non-mineral grease on the moving brake parts instead. This lubricant should be free of metals, be non-conductive, possess a high thermal resistance, have lubrication properties, offer corrosion protection and be compatible with the materials found within a typical caliper. Delphi recommends High Performance Brake Grease and Mintex recommends its Ceratec lubricant.

DRIV advises that any assembly grease must be used in moderation – areas where the brake pad back-plates come into contact with the caliper metal (such as at the ends of each pad) and the pins on multi-pistons/pots should only be greased sparingly. This video offers helpful information: https://bit.ly/2jic9ra