Parker recommends to use 46 weight "AW46" Hydrualic fluid, or 10W40 oil is preferred for your conveyors and hydraulic power units.

ISO/AW 100 is within the viscosity range of SAE 30, which was AVW’s/Tommy's “house” grade used for years when filling customer systems.

While Resolving technical issues, we have realized that there is a wide range of hydraulic fluid viscosities reccomended and used in Tommy equipment. There is some indication that the lower viscosity grades we have been using may not be suited to the clearances and operating conditions in the hydraulic pumps and motors, a potential cause of some site-specific performance issues that a few of you have experienced.   

Across the group, we have recommended ISO/AW 32, 46, and 68 hydraulic fluid, and SAE30 motor oil, and other grades as well, perhaps.  I did some reading to clear things up a little.  ISO (International standard) and AW (American standard) numbers refer to the center point of the actual viscosity range of the oil in centistokes at 40°C.  The SAE “weight” numbers also correlate to the viscosity of the oil, but that explanation is too complex for this message (which really means I don’t understand it).  A multi-weight oil like SAE 10W-30 has polymer additives that cause the oil to behave like SAE 10 oil at cold temperatures (“W”inter temperatures, the source of the W) and like SAE 30 oil at high operating temperatures.  See the attached Excel chart that shows the relative viscosity ranges of the oils pertinent to this discussion as reported in some of the documents I read.

To unify our approach, after many discussions with our primary hydraulics supplier, Tommy/A.V.W. is standardizing on a single viscosity grade for use in all equipment: ISO/AW 100 hydraulic fluid.  If this is not available, SAE30 motor oil may be substituted.  There should not be a need for multi-grade motor oil; if the wash is getting so cold as to require that, close the doors and turn on the heat – the water is going to freeze!   

This does not mean that fluid has to be replaced now, but in future recommendations, fluid change-outs, and start-ups, please adhere to this standard.