[AT] 20w Oil

James Peck jamesgpeck at hotmail.com
Tue Nov 5 08:34:26 PST 2019


We had an interesting one from early 2018. A die lubricant recovery system filtered tramp hydraulic and press slide oil out of the die lubricant mixture, water and miscible oil. We would read the refractive index and pump more miscible oil in if it got low. When we started stamping galvanized strip, the zinc caused the tramp oil to go into solution and throw the refractive index out of kilter.

Steve Offiler Mechanical Engineer <soffiler at gmail.com>; Hi Carl:

Interesting article (thanks Cecil).

The article hits the concerns of water and temperature as it relates to hydraulic systems.  Not sure you can boil that down to "...the only difference between the two types of oil has to deal with water issues in the system..."

It says that engine oil has a tendency to emulsify (absorb/hold in suspension) water; hydraulic oil does not.  It says this is a reason not to use engine oil in hydraulic systems unless specified by the manufacturer.  In hydraulics, you generally want the water to separate, not to be emulsified and carried around the system.

I suspect lubricity differences as well, but the article does not mention this.  My reason:  links provided earlier in this discussion (to Traveller ISO 46, I *think*) brought up specifications warning against the use of hydraulic oil in transmissions, differentials, etc.  Sounds like it lacks extreme-pressure additives common in engine and especially gear oils.

Carl Szabelski AT list member and tank knowledge resource <szabelski at wildblue.net>; Thanks Cecil, very interesting article.

If I read this right, the only difference between the two types of oil has to deal with water issues in the system. Since you can’t control the amount of water that might be introduced into the belly pump, using hydraulic oil could be an issue when using it in the belly pump. Don’t know if this really is an issue or not, but maybe that’s why the manuals say to not use hydraulic oils (cavitation, part wear).

I did some more looking on line last night and ran across some articles dealing with engine oils and hydraulic oils. Most of them go into the history of oils, all the way from the first non-detergent single weight oils up the multi grade oils, and into synthetics.  Seems to be a consensus that a lot of misunderstanding exists as to whether or not you need to use single weight or multi weight oils in engines and such. They also addressed things like viscosity at different temperatures, especially with multi grade oils, since this is apparently also misunderstood a lot.

I also ran across two sources of 20W-20 oil, both natural and synthetic. These were from Kendall and Mystic, and were considered to be hydraulic oils from their websites. Also noted that the prices were 2-1/2 to 5 times the price I paid for the 20W Traveller oil.

Since I’m good for now, and since I’m not in a real hurry to put this issue to bed, I’m going to keep looking into it over the winter as time allows.

Thanks to all those who spent time delving into this question.

Cecil Bearden AT list member, Oklahoma farmer, and Professional Engineer <crbearden at copper.net>; Explanation of hydraulic and motor oils used for hydraulics.

https://www.machinerylubrication.com/Read/29715/hydraulic-engine-oils


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