Hydraulic oil for old Michigan 75 loader

[donvalley]

Hi - the old Michigan 75 loader I'm restoring has very little literature available. The hydraulic oil recommended for the system simply says "hydraulic oil" ?? Would anyone know what type of hydraulic oil was used successfully in those machines?

Thank you!

 

[JHZR2]

Id suspect just an R&O type (rust and oxidation) lube of roughly 30wt viscosity.

 

[JayhawkRoy]

I found a link to a model 75A loader. The engine doesn't seem to match the Detroit Diesel that you refer to, but I would think the fluid specs would be the same.

I can't copy the specs for the fluid, but they are on page 6 of the manual. Here is the link to the manual (pdf file):
http://www.tractorparts.com/PDFs/MICHIGAN75AOperatorsManual.pdf

 

[Colt45ws]

That viscosity range in the manual would correspond to ISO 46 fluid. R&O and anti fomants. Probably many oils would meet these specs.

 

[donvalley]

The 75A loader had different engine options than the 75III. Mine is the General Motors version with the inline 4-53 diesel 2-cycle engine. But I'm sure you're right about both machines using the same hydraulic oil. Thanks to everyone for their help.

 

[George Bynum]

Originally Posted By: Colt45ws
That viscosity range in the manual would correspond to ISO 46 fluid. R&O and anti foamants. Probably many oils would meet these specs.
It also said a heavy duty hydraulic fluid meeting those specs ... hydraulic fluids, even then, had (have) anti-wear and extreme pressure (EP) additive packages. The R&O are excellent fluids, but are not optimum for the pump and (if used) hydraulic motor service. Get an ISO46 hydraulic fluid; there are dozens of good ones at reasonable prices.

 

[donvalley]

Are there advantages to using an ISO46 oil in the off-road hydraulic system of the loader, rather than a SAE 10W engine oil?

 

[zeng]

Originally Posted By: donvalley
Are there advantages to using an ISO46 oil in the off-road hydraulic system of the loader, rather than a SAE 10W engine oil?

KV@40*C of SAE 10W is slighyly typically low'ish at 40/42 cSt, I would pick ISO 46 for that slightly thicker protection.

 

[George Bynum]

Originally Posted By: donvalley
Are there advantages to using an ISO46 oil in the off-road hydraulic system of the loader, rather than a SAE 10W engine oil?
OH ARE YOU ASKING FOR REPLIES!

I'm one who feels that engine oils are ok ... BUT they are designed to "absorb" water that condenses or otherwise gets into the system. Hydraulic oils are designed to NOT emulsify. Hydraulic oils are good for years, motor oils for a year or 2.

If the system operates a large portion of it's working life at 140F or higher, the water will probably be removed from the oil.