(19)
(11) EP 1 418 221 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
23.06.2004 Bulletin 2004/26

(43) Date of publication A2:
12.05.2004 Bulletin 2004/20

(21) Application number: 03025453.6

(22) Date of filing: 05.11.2003
(51) International Patent Classification (IPC)7: C10M 169/04
// C10N40:04
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR
Designated Extension States:
AL LT LV MK

(30) Priority: 07.11.2002 JP 2002323774

(71) Applicants:
  • Nippon Oil Corporation
    Tokyo 105-8412 (JP)
  • TOYOTA JIDOSHA KABUSHIKI KAISHA
    Toyota-shi, Aichi 471-8571 (JP)

(72) Inventors:
  • Kurosawa, Osamu
    Yokohama-shi Kanagawa 231-0815 (JP)
  • Matsui, Shigeki
    Yokohama-shi Kanagawa 231-0815 (JP)
  • Morita, Eitaro
    Yokohama-shi Kanagawa 231-0815 (JP)
  • Yamamori, Kazuo
    Toyota-shi Aichi-ken 471-8571 (JP)
  • Arai, Hiroyuki
    Toyota-shi Aichi-ken 471-8571 (JP)

(74) Representative: Grünecker, Kinkeldey, Stockmair & Schwanhäusser Anwaltssozietät 
Maximilianstrasse 58
80538 München
80538 München (DE)

   


(54) Lubricating oil composition for transmissions


(57) Lubricating oil compositions for transmissions comprise (A) a mineral lubricating oil having a kinematic viscosity of from 2.3 to 3.4 mm2/s and a %Cp of 7.0 or higher defined by ASTM D 3238, as a base oil, (B) a phosphorus compound in an amount of from 0.025 to 0.05 percent by mass in terms of phosphorus based on the total mass of the composition, and (C) a viscosity index improver in such an amount that the composition has a kinematic viscosity of from 5.0 to 6.0 mm2/s, sulfur being contained in an amount of 0.15 percent by mass or less in the composition. The lubricating oil compositions are excellent in fuel efficiency and capable of improving the durabilities of gears and clutches, leading to long lasting gear change characteristics.





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