Will putting regular motor oil into a hydraulic reservior to raise the oil level up to normal hurt anything ?

We have a bobcat skid steer loader on the farm that was built in the mid 70′s. Works pretty good for its age and we don’t push it hard but it has it’s share of leaks mostly at the seals. We were told by a mechanic that works on them that if you didn’t have any hydraulic oil on hand you could put W30 motor oil in the reservior to bring it back up to proper level. Thats been a couple of years ago and now motor oil of any viscosity is being put into it. Will this damage any of the system; seals ,pump,valves etc.? The whole system will take about 13 gals. and I’m concerned that when I change the filter and top off with oil its just going to be a waste of oil and filter unless the whole system is flushed out.

4 Responses to “Will putting regular motor oil into a hydraulic reservior to raise the oil level up to normal hurt anything ?”

  • Robert B:

    it should be flushed and new filters put on.the regular oil cause gunk and deposits to get into all the parts.it also causes carbon to build up.and it breaks down with the temps that hydraulics reach.flush it and put the correct oil in it and new filters

  • CNC Guy:

    Hydraulic oil is only 10 weight the heavier viscocity will blow the seals and eventually ruin it

  • IbelieveIbinderealreadyNdonedat:

    Yup. The mechanic just wanted extra work. You will be back with a broken hydraulic system pump. You do that in emergency situations. It is not meant to stay in there. The whole system has to be flushed out and cleaned. that means parts taken apart and washed clean of oil. Brake fluid(hydraulic fluid is not oil). Oil will harden seals and neoprene causing them to leak even more. Also oil is corrosive to flexible hoses and they will crack. Oil will also burn.

  • Paul:

    I’m no hydraulics expert, but I’ve learned over the years that doing things like this (cutting corners to save a buck) usually has a bad outcome.

    Motor oil has certain additives specifically designed for auto engines, is not designed to be pressurized to the levels hydraulic systems need.

    I say: clean, flush the system, install new HYDRAULIC oil, and hope you haven’t caused any damage.

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