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Oil Change - Jet geared head lathe

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  • #16
    Originally posted by Willy View Post
    Sorry but I missed this post earlier.

    ISO 68 simply refers to the viscosity of the oil per International Standardization Organization testing methods. We are much more familiar with SAE motor oil viscosity numbers like 10,20,30 etc. An ISO 68 viscosity oil is roughly equivalent to a high 20, low 30 SAE engine oil viscosity if you want to draw a comparison that means more to you, as it relates to something you may be more familiar with.
    The "VG" only means viscosity grade and does not describe the type of oil. I'll assume for now that it is a straight hydraulic oil, which is perfectly fine for your intended use. If that is what it actually is.
    Many thanks Willy. That pretty much sums it up. This leaves me with an option of using straight 30W if I understood you correctly and all else fails. "VG" = "viscosity grade" ... of course, what else would it stand for - now I really feel like an idiot. *LOL* Thanks again.

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    • #17
      Remember that it is not so much an issue of the weight of the oil as the type of oil.
      An ISO 68 hydraulic oil would be a better choice than an automotive 30 weight engine oil even though the viscosity would be almost the same.
      Home, down in the valley behind the Red Angus
      Bad Decisions Make Good Stories​

      Location: British Columbia

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      • #18
        You will have no problem using ISO68 hydraulic oil. Look up the DTE spec sheets and you will see very minor differences none of which may be of concern for your use. NAPA sells a house brand of AW68 remarkably cheap. They are "non-detergent" and you will not have a problem with suspended particles needing a filter. For many reasons, stay away from "engine oils".

        BTW... if you do have "particles" change your oil a couple of times.

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        • #19
          has sat idle for many years
          Just curious. How many years is "many"? And after how many does one start to be concerned?
          "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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          • #20
            I have not seen anything about automatic transmission fluid in this discussion. It would seem it is a gear lube and hydraulic oil combination and lasts for a long time in transmissions. Any comments?

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            • #21
              Originally posted by wdtom44 View Post
              I have not seen anything about automatic transmission fluid in this discussion. It would seem it is a gear lube and hydraulic oil combination and lasts for a long time in transmissions. Any comments?
              Yeah.. Why not just use the appropriate lubricant?

              Also, quite a bit of ATF has a low quality base that is rancid or quickly goes rancid - all while still in the original container.

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              • #22
                Originally posted by wdtom44 View Post
                I have not seen anything about automatic transmission fluid in this discussion. It would seem it is a gear lube and hydraulic oil combination and lasts for a long time in transmissions. Any comments?
                From the Lathes UK website:


                Suitable oils
                For use in many types of machine tool - including the geared headstocks and screwcutting gearboxes of lathes and milling machines - manufacturers from the 1940s onwards often recommended an "anti-wear" Hydraulic oil such as Shell Tellus 27- although some did specify a plain mineral oil ("Vitrea" in various grades, without any additives). These lubricants can deliver their specification performance while also being thin enough to be fed through wicks - a common fitting on many older machine tools, and used to draw up oil but leaving dirt behind. They are also formulated to resist the corrosion of copper and bronze - a good thing for the bronze bearings commonly found in headstocks, aprons and screwcutting gearboxes - and not something an "ordinary" oil will have, and certainly not a motor oil (as a tip, modern motor oils are no good in older-type machine tools - they are designed for high shear rates, high-pressure pump feed and the sort of thin films that hold bearing surfaces apart at high r.p.m.) Car engine oils also contain detergents and dispersants intended to that keep particles of dirt, metal and combustion by-products in suspension. This is ideal if a filter is provided to trap the nasty bits but not so good otherwise. Oils intended for machine-tool use allow the particles to sink to the bottom of a sump and (hopefully) stay there. The writer has dismantled more than one geared headstock to find an almost solid layer of encrusted dirt, metal shaving and "bronze dust" in the base.
                Avoid the hydraulic oils intended for automatic transmission systems (ATC). These have been known to cause trouble in some machine-tool applications.
                Home, down in the valley behind the Red Angus
                Bad Decisions Make Good Stories​

                Location: British Columbia

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                • #23
                  I'd have to double check, but I think I settled on jd303 from the local farm store. I think it had the anti wear and corrosion inhibitors. Supposed to be fairly common in tractors as both gear lube and hydraulic fluid. For the price (about $30 per 5 gal) I'll never hesitate to change it.

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