How Stuff Works

Fuzz Townshend explains why getting grease right is essential for your classic

Classic car grease

Come on, admit it. When it comes to grease you buy the one that you first lay eyes on at the motor factor’s shop.

Actually, no, I’ll bet that you look at the first tube or tub and then move on to one that states that it has a high melting point, when actually, you have no idea of the working temperature of the component you’re intending on lubricating.

Besides, if the container states that the contents are a multipurpose grease, then it’ll do for everything, from spring shackles to wheel bearings, via rubber seals; right?

You'd be very wrong. Greases are possibly one of the most complex groups of lubricants utilised in motor cars. In essence, greases are a lubricant suspended in a semi-solid state, so that it can be retained in a situation where a liquid would simply leak out.

Early greases were often based upon animal fats, such as tallow – pure animal fat, without the tasty dark bits at the bottom of the dripping jar, to you and I.

’Early greases were often based upon animal fats, such as tallow'

Such greases had excellent resistance to water penetration, a bonus in situations such as wheel bearings, leaf springs etc, but their lubricating qualities became a bit iffy at higher temperatures, even though they smelled great, like granny’s kitchen on a Sunday.

As vehicles and their components became more sophisticated, greases had to be developed to withstand situations such as increased bearing temperatures due to the development of ever more efficient braking methods and, therefore, higher operating heat.

Greater loadings also meant that greases were required to work under ever harsher conditions, and the advent of ‘sealed for life’ components meant that greases needed to be able to hold on to their lubricating properties for increasing periods of time.

Following the delicious-smelling tallow (apologies to the vegetarian and vegan classic car nuts who are reading this) tallow-like greases were developed by reacting tallow with calcium-based lime to create a ‘soap’ and then adding mineral oil, thus retaining water resistance, but reducing hardening at low temps.

However, calcium-based greases were less than ideal at higher temperatures and so sodium soaps were developed, only to be replaced by lithium (again great water resistance), which in turn succumbed to clay, calcium complex, lithium complex and polyurea greases; which brings things bang up to date, for now, the latest greases may be utilised in both bearing situations and chassis component lubrication.