SAE + HTO additive versus ISO / AW for hydraulic fluid (Case 70XT)

[HoHum]

I just lost all my hydraulic fluid for my Case 70XT. The manual calls for SAE 10W30 engine oil with HTO additive (B17508). The nearest place that has this additive in-stock is nearly an hour away. I have barrels of normal hydraulic fluid (ISO / AW 46). From what I've gleaned, AW 46 is essentially a 15 weight oil with additives for protection against rust, oxidation and has anti-wear (hence the AW) and anti-foam additives.

Anyone else run normal hydraulic fluid instead of motor oil plus HTO additive? This is not a cost issue, because, based upon my calculations, the costs are similar. For me, it's more a matter of time and convenience. Thoughts?

 

[J_J]

My Case 1845c skidsteer says the same as yours, but with the option of running HY-Trans.

MY Case trenched uses ATF.

 

[HoHum]

Thanks for the reply.

I've talked to several Case service guys. The consensus is that HTO additive is designed to take motor oil and convert it to hydraulic oil by adding anti-wear, anti-foam and anti-corrosive properties. They also agreed that ISO/AW hydraulic oil already has those properties inherent to it. However, they are quick to recommend and follow what the manual states. Probably due to liability.

I would like to know anyone who has had real-world experiences with running 46 hydraulic oil in a machine that the manufacturer requires motor oil plus an additive. Anyone?

 

[MHarryE]

Thanks for the reply. I've talked to several Case service guys. The consensus is that HTO additive is designed to take motor oil and convert it to hydraulic oil by adding anti-wear, anti-foam and anti-corrosive properties. They also agreed that ISO/AW hydraulic oil already has those properties inherent to it. However, they are quick to recommend and follow what the manual states. Probably due to liability. I would like to know anyone who has had real-world experiences with running 46 hydraulic oil in a machine that the manufacturer requires motor oil plus an additive. Anyone?

Not personal experience but I can give the Caterpillar perspective. In the past we had customers using hydraulic excavators fail hydraulic pump due to water ingestion. In determining why some customers had the problem while most didn't, it was discovered that most having the problem had switched from recommended hydraulic oil for mobile equipment to industrial hydraulic oil (AW). If you look through spec sheets on AW oils, one property is they will not emulsify water. An example of typical use is a hydraulic press in a factory. While sitting, the water will separate out and can be drained. That's not typical of mobile applications. Hydraulic oils for mobile applications are capable of emulsifying a small amount of water. The hydraulic excavator pump failures I mentioned - water from normal operation would settle out overnight. When started the next day, an operator might swing the car body of the excavator, the slug of water that separated was ingested into the pump, and that slug was enough to initiate failure. I am not a Case person so I do not know about their HTO additive. However, most all Caterpillar equipment is approved to use Diesel Engine Oil (DEO at Cat) as hydraulic fluid without any additive. Our engine oil already has the properties you mention. Some machines leave the factory with DEO in their hydraulic system if they are to be used in a high ambient temperature application because 15W-40 will maintain the proper viscosity at high operating temps. DEO has one major disadvantage - it is much more expensive than hydraulic oil. It will emulsify oil very well.

https://parts.cat.com/wcs-static/pdfs/SEBU6250-19.pdf

The link is the Caterpillar fluid guide. Lengthy, but page 18 explains ability to handle water and the boldface warning not to use industrial (AW for anti-wear but that also indicates an industrial oil) and if you do, warranty is void. I believe page 26 talks about hydraulic oils and gives their selection priority. Note that DEO is in group 2 but it does give a broader temperature range than Advanced HYDO 30 in group 1.

Another reference is to Google Mobil hydraulic oils. Their oils having AW classification state they will separate water. Mobilfluid 424 does not talk about its ability to emulsify water but it is one property that makes it an excellent hydraulic oil for general mobile equipment use.