Hydraulic oil questions/Leroy

big_red_man · May 23, 2019

I need non-foaming oil of about 20 weight for my horse drawn mower gearbox. What weight is that cheapo 303 tractor hydraulic oil? Can i assume its non-foaming? Ive been using ISO 46 hydraulic oil. Is the 303 about the same?

SVcummins · May 23, 2019

303 or any tractor hydraulic oil is hydraulic oil and also gear meeting gl-5 specs . ISO 46 or any regular hydraulic oil that is not a tractor hydraulic oil is just for lubricating hydraulic pumps and valves not gears and bearings in a transmission .

4play · May 24, 2019

303 or SAE 75 or 80 gear oil would be fine. For comparison of ISO to SAE eng oil viscosity. ISO 46 is on the lighter side of SAE 20, maybe closer to SAE 15. 303 is at the heavy side SAE 20, IMO it's a little thicker than most SAE 20 engine oils. ISO 68 is a closer comparison to 303 or SAE 20, its also inline with SAE 75-80 gear oil in relation to viscosity

Like mentioned, hydraulic oils are specifically for hydraulic systems, pumps, valves etc, not necessarily for bearings, gear boxes etc, most hyd oil should have anti-foam additives though.

big_red_man · May 24, 2019

Appreciate the replies. I do know gear oil (about 90 wt) is WAY too thick. The poor old horses can?t pull a mower with oil that heavy.
Sounds like the 303 should be about right if it?s about 20 wt or so.

Brendon-KS · May 24, 2019

Don't dismiss a gear oil as being too thick just because of the number rating. Gear oils and engine/hydraulic oils have very different numbers for the same viscosity since they are rated differently - you can't use the number on the bottle to compare between them. SAE 80W gear oil has about the same viscosity as SAE 20 or 30 engine oil.

Leroy · May 24, 2019

What make and model of mower? I don't know of any mowers that should use that thin of an oil. Normal is 80-90 gear oil and they use 2 horses on a 7' bar mower but a 6' is prefered by some, 5' is hardly seen for use in Amish country. Any 5' mower is converted to either a 6' or 7' if they can find the bar off a tractor mower. And I wonder what kind of horses you think a mower with correct oil pulls to hard for them, any team should be able to easily pull a 6' mower with correct grease.

big_red_man · May 24, 2019

Boy my memory isn?t so good. Lynn R Miller wrote ?The Horsedrawn Mower Book?. He also taught the Amish how to rebuild old mowers.His book says: ?DO NOT USE 90w gear oil. Use10w foam depressed hoist oil.?
My question is what is foam depressed hoist oil? Maybe my question should be: Where do I buy foam depressed hoist oil?
What I asked was is the 303 kinda the equivalent????? Thanks, Kelly

sotxbill · May 24, 2019

(jd)303 oil is being phased out due to political activist and (JD)20t oil will be its replacement.

moresmoke · May 24, 2019

10w oil should be available from a Deere dealer. They use it in the older combines for hydraulics.

Realistically for as much use as it will get, anything slippery will work.

wrenchere85 · May 24, 2019

A non foaming oil would be a non detergent motor oil. That was one reason they used that oil in splash lubricated engines and in air compressors.

Destroked 450 · May 24, 2019

The cheap 303 should work fine for your app

Hydraulic oil questions/Leroy

big_red_man

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SVcummins

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4play

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big_red_man

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Brendon-KS

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Leroy

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big_red_man

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sotxbill

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moresmoke

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wrenchere85

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Destroked 450

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