LUBRICATING   OIL   TECHNOLOGY   -   TECHNICAL   & COMMERCIAL    ASPECTS

ORIGIN :

Crude Petrolium, generally termed as crude oil may be broadly classified by the types of fractions produced when they are refined. Basically there are three main types of hydrocarbons in crude oil.

1.   Praffin hydrocarbons.

2.                     Napthene hydrocarbons.

3.   Aromatic hydrocarbons.

In general, good quality lubricating oils are refined from paraffinic or napthenic crudes. Aromatic crudes are only used for poor quality black oil refining.

In general, paraffinic lubricants have good natural resistance to oxidation, good thermal stability, good lubricating properties, high pour point, high flash point, low volatility and a high viscosity index (90 to 115). When used as lubricants in internal  combustion engines, however they tend to form hard carbonaceous deposits of a very closed grained nature. When oxidation does occur they tend to  form weak organic acids which attack certain non-ferrous alloys.

Napthalene oils have a lower viscosity index (15 to 75) and low pour points which make them suitable for low temperature applications. When burnt in diesel engines they form fairly soft, friable deposits. Their volatility is however, higher than paraffinic oils of similar viscosity, the flash point is lower and oxidation resistance generally poorer. When oxidation occurs, the tendency is to form sludge type deposits rather than acids.

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