Exxon Research and Engineering Company

Andre E Asselin

Lilianna Z Pillon

Gerald A MacAlpine

Lloyd E Reid

Patrick Desmond Vernon

Lillanna Z Pillon

Partick M Halls

Liliana Z Pillon

Foaming of a lube oil comprising a base stock derived from wax isomeration and an additive package is effectively reduced to within specification limits of 50 ml/ml over a temperature range of from at least 24.degree. C. to 93.5.degree. C. by adding to the oil an effective amount of an antifoamant exhibiting a spreading coefficient of at least about 2 mN/m. This has been found to be particularly effective in reducing foaming of lube oils containing a mixture of a wax isomerate oil and a petroleum oil fraction. Antifoamants typically used with conventional lube oils containing one or more petroleum fraction base stocks, but which do not exhibit a spreading coefficient of at least 2 mN/m with the wax isomerate containing oil, have been found not to be effective in reducing the foaming of the oil.

Method for reducing foaming of lubricating oils

A combination of a fluorosilicone antifoamant and a polyacrylate antifoamant have been found to be effective in reducing foaming of lubricating oils at both low and high temperatures and without degrading the air release time to the extent that would occur with a conventional silicone antifoamant. Neither type of antifoamant is effective in reducing foaming at both low and high temperatures by itself.

Antifoaming agents for lubricating oils (law455)

A combination of succinic anhydride amine derivatives and tetra propenyl succinic acid derivative rust inhibitors has been found to be synergistically effective in reducing the formation of rust in lubricating oils.

Lubricating oil for inhibiting rust formation

Lube oil basestocks having an oil/water interfacial tension (.gamma. o/w) of less than 41 mN/m, preferably less than about 35 mN/m which exhibit unacceptable demulsibility can have their demulsibility performance improved by contacting said lube oil basestock with an acidic ion exchange resin, such as Amberlyst AR-15, or with silica. The treated lube oil base stock exhibits an oil/water interfacial tension (.gamma. o/w) of at least about 41 mN/m, preferably at least about 42 mN/m.

Method for improving the demulsibility of base oils

The addition of a polyalkylmethacrylate having a weight average molecular weight of at least 600,000 has been found to be effective in reducing the pour point of a wax isomerate to a level that cannot be obtained with conventional pour point depressants. In a preferred embodiment, the wax isomerate is a slack wax isomerate.

Wax isomerate having a reduced pour point

The rust inhibiting and demulsibility performance of a lubricating oil can be synergistically enhanced by incorporating a rust inhibitor having at least one COOH acid group and a particular class of pyridine derivatives.

Lubricating oil having improved rust inhibition and demulsibility

The rust inhibition capability of a lubricating oil having an average ring number per mole of less than 1.5 can be enhanced by adding a rust inhibitor that is capable of reducing the oil/water interfacial tension to between about 1 to about 4 mN/m.

Lubricating oil having an average ring number of less than 1.5 per mole

A combination of a low and a high molecular weight polyalkylmethacrylate has been found to be effective in reducing the pour point of a wax isomerate to a level that cannot be obtained with conventional pour point depressants. In a preferred embodiment, the wax isomerate is a slack wax isomerate.

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Andre E Asselin