Clean performing gear oils

A lubricant essentially devoid of carboxylic ashless dispersants comprising:

• a) a base oil having a kinematic viscosity at 100.degree. C. ranging from about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) a dispersant Viscosity Index Improver at a concentration of from 0.1 to 10.0 percent by weight;
• and
• c) a gear performance additive at a concentration of from 3.0 to 10 percent by weight and wherein said additive is at least one extreme pressure agent containing at least 25 percent by weight sulfur;
• and wherein the resulting lubricant has a Brookfield Viscosity at -12.degree. C. ranging from about 1,000 to about 150,000 cP.

A method for reducing the carbon and varnish production in a lubricated axle or manual transmission, said method comprising the use of a gear oil comprising:

• a) a base oil in the amount of about 88.0 to about 98.5 percent by weight, said base oil having a kinematic viscosity at 100.degree. C. ranging from about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) about 0.1 to about 10 percent by weight of a polymer comprising the following monomers:
• (i) a C1-C6 alkylmethacrylate of the formula:
• ##STR10## where R.sup.1 is alkyl of 1 to 6 carbon atoms;
• (ii) a C7-C14 alkylmethacrylate of the formula:
• ##STR11## where R.sup.2 is alkyl of 7 to 14 carbon atoms;
• (iii) A C1-C20 alkylmethacrylate of the formula:
• ##STR12## where R.sup.3 is alkyl of 15-20 carbon atoms;
• and (iv) a N,N-dialkylaminoalkyl(meth)acrylamide of the formula:
• ##STR13## where R.sup.4 is hydrogen or a lower alkyl group;
• R.sup.5 or R.sup.6 are hydrogen or a hydrocarbon selected from the group consisting of alkyl, aralkyl cycloalkyl, aryl and alkaryl, including such radicals when inertly substituted;
• R" is a hydrocarbon group selected from the group consisting of alkylene, aralkylene, cycloalkylene, arylene and alkarylene, including such radicals when inertly substituted;
• and A is selected from --O--, --S-- and --NH--;
• wherein said polymer comprises 0 to 50 percent by weight of said C1-C6 alkylmethacrylate, 30-85 percent by weight of said C7-C14 alkylmethacrylate, 3-50 percent by weight of said C15-C20 alkylmethacrylate and 2-10 percent by weight of said N,N dialkylaminoalkyl(meth)acrylamide and
• c) about 0.1 to 10 percent by weight of an extreme pressure agent containing at least 25 percent by weight sulfur.

A lubricant comprising:

• a) a base oil in the amount of about 88.0 to about 96.0 percent by weight, said base oil having a kinematic viscosity at 100.degree. C. of about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) a dispersant pour point depressant in the amount of about 0.1 to about 3.0 percent by weight;
• and
• c) a gear performance additive in the amount of about 3.0 to about 10.0 percent by weight and wherein said additive is at least one extreme pressure agent containing at least 25 percent by weight sulfur;
• and wherein the resulting lubricant has a Brookfield viscosity at -12.degree. C. ranging from about 1,000 up to about 150,000 cP.

A gear oil comprising:

• a) a base oil having a kinematic viscosity at 100.degree. C. ranging from about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) a combination of a dispersant pour point depressant and a dispersant Viscosity Index Improver, said combination being at a concentration for 0.1 to 3.0 percent by weight;
• and
• c) at least one extreme pressure agent at a concentration from 3.0 to 10 percent by weight and wherein said extreme pressure agent is at least 30 percent by weight sulfur;
• and wherein the resulting gear oil has a Brookfield Viscosity at -12.degree. C. ranging from about 1,000 to about 150,000 cP.

A gear oil having a Brookfield Viscosity at -12.degree. C. or -26.degree. C. ranging from about 1,000 up to about 150,000 cP, said gear oil comprising:

• a) a base oil in the amount of about 88.0 to about 98.5 percent by weight;
• said base oil having a kinematic viscosity at 100.degree. C. of about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) a functionalized poly(meth)acrylate (PMA) in the amount of about 0.1 to about 3.0 percent by weight;
• and
• c) a gear performance additive containing at least 25 percent by weight sulfur in the amount of about 3.0 to about 10.0 percent by weight.

A method for reducing the sludge production in a lubricated gear box or axle comprising adding to said gear box or axle:

• a) a base oil in the amount of about 88.0 to about 96 percent by weight, said base oil having a kinematic viscosity at 100.degree. C. ranging from about 4.0 to about 41.0 cSt and a Viscosity Index ranging from about 60 to about 140;
• b) about 0.1 to about 10 percent by weight of a polymer comprising the following monomers:
• (i) a C1-C6 alkylmethacrylate of the formula:
• ##STR14## where R.sup.1 is alkyl of 1 to 6 carbon atoms;
• (ii) a C7-C14 alkylmethacrylate of the formula:
• ##STR15## where R.sup.2 is alkyl of 7 to 14 carbon atoms;
• (iii) A C15-C20 alkylmethacrylate of the formula:
• ##STR16## where R.sup.3 is alkyl of 15-20 carbon atoms;
• and (iv) a N,N-dialkylaminoalkyl(meth)acrylamide of the formula:
• ##STR17## where R.sup.4 is hydrogen or a lower alkyl group;
• R.sup.5 or R.sup.6 are hydrogen or a hydrocarbon selected from the group consisting of alkyl, aralkyl cycloalkyl, aryl and alkaryl, including such radicals when inertly substituted;
• R" is a hydrocarbon group selected from the group consisting of alkylene, aralkylene, cycloalkylene, arylene and alkarylene, including such radicals when inertly substituted;
• and A is selected from --O--, --S-- and --NH--;
• and
• wherein said polymer comprises 0 to 50 percent by weight of said C1-C6 alkylmethacrylate, 30-85 percent by weight of said C7-C14 alkylmethacrylate, 3-50 percent by weight of said C15-C20 alkylmethacrylate and 2-10 percent by weight of said N,N dialkylaminoalkyl(meth)acrylamide and
• c) about 0.1 to 10 percent by weight of an extreme pressure agent containing at least 25% by weight sulfur.