Cat Hydraulic Oil (HYDO) - Hydraulic System
Cat Hydraulic Oil is formulated with a balanced additive
system, including detergents, rust inhibitors, antiwear
agents and defoamers. It will offer maximum protection
against mechanical wear, rusting and corrosive wear in
all hydraulic and hydrostatic transmission systems.
Cat Hydraulic Oil should be used to achieve maximum
life and performance from hydraulic system components
and hydrostatic transmissions. Use of Cat Hydraulic Oil
is recommended in most hydraulic and hydrostatic
If higher viscosities are required because of high
ambient temperatures, the following Caterpillar oils can
Cat Diesel Engine Oil DEO (CF-4/CG-4)
Cat Transmission/Drive Train Oil (TDTO)
If Cat oils cannot be used, the following commercial
classifications can be used in the hydraulic system:
Premium industrial hydraulic oils that have passed the
Vickers vane pump test (35VQ25) and/or have a
minimum of 0.09% zinc additive may also be used.
These oils should have antiwear, antifoam, antirust and
antioxidation additives for heavy duty use as stated by
the oil supplier. ISO viscosity grade of 46 would
normally be selected.
Caterpillar Transmission/Drive Train Oil
Caterpillar TDTO TO-4 is balanced to give maximum
frictional material life in power shift transmissions. TO-4
oil specifications include frictional and gear wear
requirements. TO-4 oil is offered in several viscosity
grades, including SAE 50, for maximum component life
at high ambient temperatures and heavy duty cycles.
TO-4 is formulated for transmissions and drive
trains only. Using TO-4 in an engine would result in
shortened engine life.
Do not use engine oils for lubricating transmissions
recommendation can cause shortened transmission
life due to material incompatibility and Inadequate
frictional requirements for disk materials.
Caterpillar does not currently offer multi-grade oils for
use in transmissions. Multi-grade oils which use high
molecular weight polymers as viscosity index improvers
lose their viscosity effectiveness (permanent and
temporary shear), and are therefore not recommended
for transmission and drive train compartments. The
Caterpillar TO-4 specification includes a test for
multigrade oil shear stability: oils that meet this
specification may be available in the future.
Transmission Lubricant Viscosity Recommendation
The following table lists TDTO viscosity grades,
quantities, and corresponding par numbers available
from your Caterpillar dealer.
CATERPILLAR TRANSMISSION/DRIVE TRAIN OIL
(5 US gal)
(55 US gal)