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Previously, the selection of the correct lubricant to use in Komatsu products was very simple as, with very few exceptions, either a SAE 10W or a SAE 30 weight engine oils were used in all compartments. There were a few exceptions, like the one in the fine print of the Operation and Maintenance Manual that recommended the use of Tractor Hydraulic Fluid in wheel loader axles instead of engine oil, but generally it was either SAE10W or SAE 30 engine oil.

However, recent developments in friction materials that allow more compact clutch designs, and the creation of engine oils that are so slippery they prevent the positive engagement of transmission clutch packs have created the need for specialized lubricants and hydraulic fluid. Additionally, the apparent autonomy of the KAIC Parts Department in promoting “branded” oil has, to a certain degree, confused the situation.

Thus, the purpose of this memorandum is to provide clear information on the selection of oils that accurately reflect Komatsu’s recommendations as expressed or discussed in the following:

  • Applicable Operation and Maintenance Manuals.
  • P&SN A930243 of 12/09/1993. Hydraulic Oil Selection WA700-1, WA800-1.
  • Installation Manual (P&SN) BA00013 of 11/01/2000. Transmission Oil.
  • Installation Manual (P&SN) BT02024A of 08/05/2002. WA Axle Oil.
  • P&SN AR01050 of 11/30/2001. Friction Modifiers in WB140-2, WB150-2 axles.
  • Ohkawa, S., Konishi, A., Hatano, H. and Voss, D. “Pump Failures in Various Type Hydraulic Fluids” Hydraulic Failure Analysis: Fluids, Components, and System Effects ASTM STP 1339, G.E. Totten, D.K. Wills, and D. Feldmann, Eds., American Society for Testing and Materials. Deals with the effects of different types of hydraulic fluids on a Komatsu HPV35+35 piston pump.
  • Komatsu Parts Policy Letter (PPL) 649 of November 15, 2002.
  • P&SN AR00051 of 11/27/2000.

For operation in temperatures above +50F, the best choice of oil would be SAE15W-40. As a minimum, this oil must meet API specification CD, CD/SF. The currently effective CF-4 is better, the 1998 CH-4 specification is better yet, but the just released CI-4 is the best yet. CI-4 will be required for the new generation engines that use very low sulfur fuels and exhaust gas recirculation or EGR. Consult the Operation and Maintenance Manual for recommendations below +50F.


  • Komatsu Bulldozers, Wheel Loaders, Trucks and Graders with planetary transmissions:
    • SAE30 engine oil may be used if it meets the older API CD Specification. According to P&SN BA00013, do not use oils meeting the new CF-4, CG-4, or subsequent specifications in this series. They are too slippery and failures may result.

    • Specially formulated power train oils may be used. These are identified by Komatsu as TO10, TO30 and TO50. The Komatsu America product equivalent to SAE 30 CD engine oil is Heavy Duty Trans Fluid 30, which has been, renamed Power Train Oil TO.

  • Komatsu Bulldozers Such as D32E-1A, D32P-1A, D38E-1A, D39E-1A, D39P-1A, and –3 Wheel Loaders with countershaft transmissions:
    • Selecting the correct oil for these transmissions can be particularly confusing as the O&M Manuals for these tractors direct the use of SAE10W Heavy Duty Transmission Fluid (HDTF), but Parts Policy Letter (PPL) 649 of November 15th, 2002 states that HDTF has been renamed Powertrain Oil TO. PPL 649 further states that it will replace API CD engine oils previously recommended in Komatsu powershift transmissions.

    • Installation Manual (P&SN) BA00013 specifically deals with the new Komatsu transmission oil specifications and makes the following points:
      • Do not use CF-4, CG-4, or subsequent specifications engine oils in Komatsu transmissions (they are too slippery).

      • TO10, TO30, and TO50 transmission oils are the recommended replacement for SAE10W, 30 and 50 weight CD engine oils.

      • The formulation of these Komatsu branded TO oils is so close to the Allison C4 or Caterpillar TO-4 specification that the use of oils meeting these specifications won’t hurt anything.

  • Komatsu –1 Wheel Loaders with countershaft transmissions:
    • Same as above, but use the SAE30 weight grade.

The correct lubricant to prevent brake chatter is what Komatsu refers to as HTF or Hydraulic Trans Fluid. The Komatsu part number is 1400138H2. It is generally known in the industry as a Tractor Hydraulic Fluid or THF, and is specially formulated to enhance the smooth operation of wet brakes. Other similar products are Chevron 1000 THF (Previously Chevron Tractor Hydraulic Fluid.) and Mobilfuid 424. P&SN/Installation Manual BT02024A of August 5, 2002 concerns Axle Oils for Wheel Loaders.

If one of the previously recommended oils is not available, an alternate oil for these applications is SAE 30 weight CD engine oil that has been treated with not more that three percent (3%) by volume Friction Modifier 1400117H91. It is important that the 3% mix ratio not be exceeded, as the effectiveness of the brakes will be reduced. (It is understood that if the brakes are accidentally “overdosed” with Friction Modifier, brake operation will usually return to normal after the mixture has been reduced to 3% or less in 50 to 100 hours of operation. This occurs because Friction Modifier is a “sacrificial surface treatment” that wears off.) Please P&SN AR01050 of November 30, 2001 for WB applications.

There has been a lot of discussion on this subject, but as of this date, the only product recommended by Komatsu for hydraulic system use is SAE10W engine oil that meets API specification CD (or later specification in this series) or MIL-L-2104. At this time, the use of AW series hydraulic oils, such as AW46 are not recommended.

P&SN AR00051 of 11/27/2000 discusses different types of biodegradable hydraulic oils and makes recommendations for their use in Utility Models. It should be noted that this P&SN does not address the larger construction or mining machines. If it is there is a need to use biodegradable oils in a construction or mining machine, it is suggested that the application be discussed with the KAIC District Service Manager, and if needed, a SEST request be filed.

If you are confused or in doubt about what oils to use in Komatsu Products, you won’t go too far wrong with the following during ambient conditions that are generally encountered in our service territory:

  • Engines
    15W-40 that at least meets API specification CD. API specifications CF-4, CH-4, or CI-4 are better yet.

  • Planetary Transmissions in Tractors or Wheel Loaders
    SAE30 API specification CD or TO oil such as Komatsu Heavy Duty Transmission Fluid (HDTF) TO30 or CAT TO-4. Do not use a CF-4, CG-4, or CI-4 specification oil. Do not use HTF or Hydraulic Trans Fluid.

  • Counter Shaft Transmissions in WA-1 Wheel Loaders
    Same as above.

  • Counter Shaft Transmissions in Small Komatsu Bull Dozers & –3 Wheel Loaders
    SAE10W API specification CD or TO oil such as Komatsu Heavy Duty Transmission Fluid (HDTF) TO10 or CAT TO-4. Do not use a CF-4, CG-4, or CI-4 specification oil. Do not use HTF or Hydraulic Trans Fluid.

  • Wheel Loader Axles with Wet Brakes & Grader Differentials with Wet Brakes
    Komatsu HTF or Hydraulic Trans Fluid or the industry standard Tractor Hydraulic Fluid (THF) like Chevron 1000 THF or Mobilfluid 424.

  • Hydraulic Systems
    SAE 10W engine oil.

Hopefully the information contained in this memo will be helpful and aid in the use of the correct lubricants. It is being distributed first by e-mail and then by mail. Other reference material will be included with the mail distribution. If you have any questions or comments about this, please contact me at the Kent branch (253) 872-3500 or by e-mail.