Patents by Inventor David Gary Lawton Holt

David Gary Lawton Holt has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6825154
    Abstract: Lubricating oil formulations comprising base oil, sulfur-phosphorous anti-wear/extreme pressure agents and hindered phenol antioxidants which anti-wear/extreme-pressure agents and hindered phenolic antioxidants are prone to crystal formation wherein the base oil is characterized as having a saturates content of less than 99% are stabilized against crystal formation by the addition of a minor amount of a high molecular weight di- or polycarboxylic acid anhydride, or mixture thereof.
    Type: Grant
    Filed: July 22, 2002
    Date of Patent: November 30, 2004
    Assignee: ExxonMobil Research and Engineering Company
    Inventor: David Gary Lawton Holt
  • Patent number: 6689726
    Abstract: Lubricating oil formulations comprising base oil, sulfur-phosphorous anti-wear/extreme pressure agent and hindered phenol antioxidant, which combination of extreme pressure agent and hindered phenol antioxidant produces crystals and containing antioxidants, wherein the base oil is characterized as having a saturates content of 99 wt % or more is stabilized against crystal formation by the addition of a minor amount of high molecular weigh di- or polycarboxylic acid, or anhydride and an ester.
    Type: Grant
    Filed: June 17, 2002
    Date of Patent: February 10, 2004
    Assignee: ExxonMobil Research and Engineering Company
    Inventor: David Gary Lawton Holt
  • Patent number: 6187723
    Abstract: A lubricant composition is described, particularly for engine oils, comprising a base oil of viscosity from 3 to 26 cSt (mm2/s) at 100° C. and an antiwear additive combination comprising (a) an oil soluble or oil dispersible phosphorus-free organo-molybdenum compound, (b) an ashless, sulfur-containing organo-phosphorus compound, and optionally (c) a zinc thiophosphate compound selected from one or more of zinc dialkyldithiophosphate, zinc diaiyldithiophosphate, zinc alkylaiyldithiophosphate and zinc arylalkyldithiophosphate. The molybdenum compound may be a carbamate, e.g., MoDTC but is preferably nitrogen-free, e.g., a carboxylate.
    Type: Grant
    Filed: December 12, 1997
    Date of Patent: February 13, 2001
    Assignee: Exxon Research and Engineering Company
    Inventors: David Gary Lawton Holt, Patrick Desmond Fraser Vernon, John Ian Atherton
  • Patent number: 5744434
    Abstract: A synthetic ester composition which exhibits thermal and oxidative stability, lower friction coefficient and lower wear, wherein the ester composition comprises the reaction product of: a branched or linear alcohol having the general formula R(OH).sub.n, wherein R is an aliphatic or cyclo-aliphatic group having from about 2 to 20 carbon atoms and n is at least 2; and at least one branched mono-carboxylic acid which has a carbon number in the range between about C.sub.5 to C.sub.13 ; wherein the synthetic ester composition has between about 5-35% unconverted hydroxyl groups, based on the total amount of hydroxyl groups in the branched or linear alcohol.
    Type: Grant
    Filed: March 14, 1996
    Date of Patent: April 28, 1998
    Assignee: Exxon Chemical Patents Inc.
    Inventors: Richard Henry Schlosberg, Haven S. Aldrich, Lavonde Denise Sherwood-Williams, John S. Szobota, Martin Anthony Krevalis, Daniel P. Leta, David Gary Lawton Holt, Fay H. Gordon