Steward Enterprise, Inc.


Below are answers to questions we get asked often!

What does ISO mean?
ISO refers to the viscosity grade of the hydraulic oil.

What is the standard ISO?
ISO 46 is an ISO standard grade. It refers to the oil's kinematic viscosity in centistokes (Cst) at 40 degrees Celsius - plus or minus 10 percent. So, an ISO VG46 oil has a viscosity of between 41.4 and 50.6 centistokes (Cst) at 40C. See chart below.

What are R&O Hydraulic Oils?
They are hydraulic oils with improved anti-rust and anti-oxidation properties. Hydraulic Oils with an AW (anti-wear) additive package could be labeled (R&O)(AW) Hydraulic Oil.

What oils contain viscosity improvers?
Oils with the terms MV, MG, MW and HVI contain viscosity index improvers which modify the rate of change in viscosity with temperature. Basically, all these terms pretty much mean the same thing.

What are the acronyms related to oil?
AW = Anti-Wear oil
HL = Rust and oxidation hydraulic oil ISO classification
HM = Rust and oxidation, anti-wear, hydraulic oil ISO classification
HR= ISO classification of a viscosity improved rust and oxidation oil
HV= ISO classification for a viscosity improved, anti-wear oil
HVI = High viscosity index
MV = Multi-viscosity
MG = Multi-grade
MW = Multi-weight
R&O = Rust and oxidation
RO = Rust and oxidation
VG = Viscosity grade
VI = Viscosity improved


Steward Enterprise Inc. | 31 Apache Ct. | Appleton, WI 54911 | (920) 734-4146
© 2002-2015 Steward Enterprise Inc.