Lacquer

A deposit resulting from the oxidation and polymerisation of fuels and lubricants when exposed to high temperatures. Similar to, but harder, than varnish.

Laminar particles

Particles generated in rolling element bearings, which have been flattened out by a rolling contact.

Lead naphthenate

A lead soap of naphthenic acids, the latter occurring naturally in petroleum.

Light obscuration

The degree of light blockage as reflected in the transmitted light impinging on the photodiode.

Liquid

Any substance that flows readily or changes in response to the smallest influence. More generally, any substance in which the force required to produce a deformation depends on the rate of deformation rather than on the magnitude of the deformation.

Load-carrying capacity

Property of a lubricant to form a film on the lubricated surface, which resists rupture under given load conditions. Expressed as maximum load the lubricated system can support without failure or excessive wear.

Lubricant

Any substance interposed between two surfaces in relative motion for the purpose of reducing the friction and/or the wear between them.

Lubricity

Ability of an oil or grease to lubricate; also called film strength.