Grease Guide: Lithium, Calcium and High-Temperature Grease, NLGI Grades

Grease stays where oil would run off. That makes it the right lubricant for bearings, pins, bushes, chassis points and slow-moving parts on vehicles, railways, construction equipment and factory machines. This guide explains grease types, NLGI grades, how to choose grease for heat, water and heavy loads, and how much to apply.

Buy: Z Premium MP3 Grease, from 1 kg to 182 kg packs.

What grease is made of

Grease is a base oil (usually mineral, sometimes synthetic) held in a thickener, like a sponge holding water, plus additives for wear, extreme pressure, rust and oxidation protection. Under load the thickener releases oil to lubricate the surfaces, and it reabsorbs the oil when the load drops.

Common grease types

NLGI grades: how stiff the grease is

The NLGI number measures consistency, from 000 (almost fluid) to 6 (block grease).

• NLGI 00–0: semi-fluid greases for centralised lubrication systems and enclosed gears
• NLGI 1: softer greases for low temperatures and long lines
• NLGI 2: the most widely used grade for bearings and general greasing
• NLGI 3: stiffer greases for high-speed bearings and vertical shafts

How to choose grease

1. Temperature: check the bearing’s operating temperature against the grease’s dropping point and recommended range. Choose lithium complex or clay greases for high heat.
2. Water: calcium-based greases resist washout in wet and outdoor conditions.
3. Load: heavily loaded or shock-loaded parts need EP greases, sometimes with molybdenum disulphide (moly).
4. Speed: high-speed bearings need lower base-oil viscosity, and slow, heavy bearings need higher.
5. Compatibility: do not mix different thickener types. Purge old grease fully when you change type.

How much grease to apply

Over-greasing is one of the most common causes of bearing failure. Too much grease churns, overheats and pushes past seals. As a general rule, fill a bearing about one-third to one-half full, and relubricate in small amounts at regular intervals rather than in large amounts occasionally. Clean grease nipples before applying, and use a dedicated grease gun for each grease type.

Common greasing mistakes

• Using one grease for every application regardless of heat, water or load
• Mixing incompatible greases in the same bearing
• Pumping grease until it comes out of the seal
• Storing open grease buckets where dust and water get in
• Ignoring hardened or discoloured grease, a sign of overheating or contamination

Z Premium greases

Z Premium manufactures multipurpose, high-temperature, wheel bearing, calcium and railway greases. They are supplied to railways, construction companies, workshops and factories, in packs from small containers (including 10 kg) up to bulk quantities, with technical data sheets on request. See the full grease range and our lubricants for railways and construction fleets.

Frequently asked questions