Products are generally rated to around 1,100 °C, a ceiling set by the melting point of copper. The grease carrier burns off well below that, which is normal and expected: it is the copper film left behind that does the work at high temperature. Check the specific product data rather than assuming, since carriers and additive packages differ, and remember that a rating describes the compound, not the fastener or the joint around it.

Because copper and stainless steel form a galvanic couple. With any moisture or electrolyte present, current flows between the two metals and drives corrosion, which is precisely the failure the compound was applied to prevent. Many marine, chemical and process specifications prohibit copper compounds on stainless outright for this reason. Use a nickel-based or metal-free product on stainless assemblies, and treat the material pairing as the first selection question rather than the temperature.

Copper is attacked by ammonia, so it is unsuitable for ammonia refrigeration and related plant. It is excluded from nuclear service, where copper and other low-melting-point metals are restricted, and from food, beverage and pharmaceutical production where metal contamination of product is unacceptable. It is also avoided where copper particles would interfere with inspection, electronics or sensitive instrumentation. In each of these cases a nickel or metal-free compound is the direct substitute.

Yes, and this is the most commonly missed point. Anti-seize is a lubricant, so it lowers thread friction sharply and a given torque produces substantially more bolt tension than it would dry. Applying a dry-torque specification to lubricated threads over-tensions the fastener and can yield or break it, or crush the joint. Use the reduction factor stated by the fastener or compound manufacturer, and never assume the dry figure still applies.

It has traditionally been used this way, but many engine and plug manufacturers now advise against it, because modern plugs are supplied with a plated or coated thread that already performs this function, and adding a lubricant leads to over-tightening and damage to the cylinder head thread. Follow the engine manufacturer's instruction rather than general practice. Where anti-seize is specified, apply it sparingly and well away from the electrode.

A thin, even film on the male thread is sufficient. More is not better: excess is squeezed out of the joint, attracts dirt, can contaminate surrounding surfaces and does nothing for the thread. Avoid applying it to blind holes in quantity, where trapped compound is effectively incompressible and can crack a casting. Keep it off friction surfaces such as brake pads and discs, and off electrical contact faces.

Keep containers closed, because the carrier can dry out and the solids settle; stir before use if separation has occurred. Store away from extremes of temperature and out of direct sunlight. Wear gloves and eye protection, since these compounds are persistent, difficult to remove from skin and stain heavily. Keep a dedicated brush with the tin rather than sharing one between different compounds, which cross-contaminates and defeats a deliberate choice of metal-free product.