I have a new to me 2006 link belt 330lx with 8900 hours, unknown history of maintenance, so I have no base oil analysis. I am new to large equipment, so I asked the dealer about changing the hydraulic oil with new, they said the oil is still good and only recommended only changing all the filters. This is based on a Nephron filtration system that suppose to filter down to 1 micron. I would hate to waste oil, so what is the best course of action in this case? Also, the service manual specs ISO VG 46, is this different from AW 46? Does it hurt to mix hydraulic oils as long as they are 46?
If you are changing the oil make sure what the specification requires for zinc content. Some excavators such as Hitachi and John Deere require zinc free oil. If zinc enters the hydraulic system it reacts with other metals especially the tank and causes the oil the form a thick sludge layer.
I think the VG is a multi weight oil, not a fixed viscosity? If your dealer sez it's okay, run it and start taking oil samples, the lab will let you know if you need to have the filter cart run or change the oil out.
AW stands for "Anti-Wear" - if it was multi-viscosity it would have the suffix MV. An AW-rated oil will contain the necessary anti-wear additives for hydraulic systems. VG simply stands for "Viscosity Grade". A VG oil will not necessarily contain the right additives for hydraulic use. A lot of Service Manuals are full of gobbledegook, because the people who wrote them had no idea about oils. In the case of the OP I would opine that the oil he should be looking for in a hydraulic system is an ISO AW46, not a VG46.
ISO VG 46 only means that the viscosity is 46 mm2/s (cSt) at 40 deg C plus/minus 10%. It does not give any indication of the other characteristics of the oil, like its resistance to oxidation or antiwear performance. The best way to avoid costs is to take a representative oil sample and have that analyzed. Pay regard especially to wear metals, viscosity, water inclusion and particle count. If those values are ok, there is no need to change the oil. AW 46 means a ISO VG46 oil with antiwear additives. Thus, each AW 46 can be regarded as a ISO VG 46 oil, but not the other way around. Apart from a antiwear additive hydraulic oils may contain antioxidaziation additives that prolong the oil life. Some equipment needs socalled zincfree hydraulic oils that tend to shed water better so it can be easily drained. You better consult the dealer about the exact specification of the oil required - ISO VG 46 tells only part of the story. Hydraulic oils with the same specifications can usually be mixed without adverse effects. As long as you keep dirt and water out of the system and do run the oil at moderate temperature hydraulic oil may last quite long.
romke, the problem the OP has is that because he bought the machine used he doesn't even know if the oil that's in there now is the correct oil for the machine so having the oil analyzed is probably no use to him whatsoever. If it was mine in view of the fact it has an unknown previous oil change history it would be getting a complete oil & filter change and filled with a premium AW46 hydraulic oil. Oil & filters are cheap compared to pumps, control valves, & cylinders.
Which is what I ended up doing, or I should say I changed the oil i the 42 gal hydraulic tank and all the filters. I ended up using CNH AW46 oil, what the LB dealer stocked and uses in all the rentals they have. I have put about 50 hours on it, should I sample now?
If you want to have a database of information going forward regarding your oil condition, now would be a good time to sample.