Snamprogetti

Agip Petroli

Luigi Imparato

Giuseppe Mancini

Silvano Fattori

Enzo Rossi

Giampaolo Gerbaz

Dario Schillani

Enrico Betta

Franco Berti

A process for preparing viscosity index improvers for lubricating oils consisting of thermally cracking a solution of an olefin copolymer in mineral oil at a temperature of between 250.degree. C. and 350.degree. C. in an inert atmosphere said solution containing free radical scavengers.

Process for preparing viscosity index improvers for lubricating oils by

Organic esters, to be employed to make up lubricating compositions are disclosed, said esters being the products of the reaction between a diol and a triol, on the one hand, and a mixture of saturated monocarboxylic acids, on the other hand. The ratios of the diol to the triol (molarly) and the structure and number of carbon atoms of the saturated monocarboxylic acids are critical. Critical values are given, as well as examples of practical use; the viscosity and viscosity index properties of the novel esters out do those of the conventional esters to a degree.

Organic ester for use in lubricant compositions

An ester, adapted for use as a component of a multigrade lubricating oil, is prepared by reacting:

Organic esters for lubricating compositions

A mineral or synthetic lubricating oil is protected against oxidation by dissolving therein, at a temperature not higher than 80.degree. C, a 3-aza-6a-thio-thiophthene or a 3,4-diaza-6a-thio-thiophthene represented by the general formulae: ##STR1## wherein, R, R.sub.1 and R.sub.2, the same or different, represent hydrogen, alkyl, cycloalkyl, aryl, alkylaryl, arylalkyl or aminoaryl.

Lubricating compositions inhibited against oxidation by addition thereto

This invention relates to esters prepared by reacting

Esters as components of lubricants

A composition comprising a poly-alkyleneglycol is stablized against molecular degradation and viscosity loss at elevated temperatures by about 0.1 to about 10% by weight of an arylhydroquinone such as p-acetylphenylhydroquinone.

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Milan, Italy

Luigi Imparato