In Reply to: Re: The Hydraulic Oil Story posted by TheOldHokie on December 27, 2013 at 20:00:54:
My 640 owners manual says 9 quarts of 90 or 7 quarts of 90 and 2 quarts of 80 if the tractor is used below 10 degrees.The chart clearly ids the oil as ep gear gear oil.One joker post this same chart and said Ford never used gear oil.The info is right beside the word tractors below the red panel.Lets get back to basics and throw all the charts out.My tractor lift works year round with 90 wt oil.With 134 it wont work in summer.My worn out pump works with the oil specified by Ford Motor Co.You do have a vested interest in selling your conversion pump to replace the vane pump.The vane pump can be repaired with Vickers parts.Theres a good hydraulics shop near me and I have talked with them about vane pumps.A hydraulic tech told me that worn pumps have what they call slippage when the oil gets hot.In case you think I know nothing about hydraulics I have worked with hydraulics since the mid 50s .I worked putting new back hoes on tractors and had to fill and bleed the systems.Theres a machinist on utube who straightens propeller shafts.To quote him.If I were selling new shafts I would tell the boat owner he needs a new shaft but I fixed his shaft for half the price of a new one.
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