I run hydraulic oil as often as I can get it, in all of my turbo or naturally aspirated diesels summer and winter.

Generally I can run 100% light/medium hydraulic oil down to -0°/-20° F, and thin it with kerosene for lower temperature operation.
Heavy hydraulic oil may need to be thinned at +40° F and lower.

There are NO concerns about lubricity.
Few hydraulic oils have a cetane number below 50.
Many common hydraulic oils are close to diesel viscosity.


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__________________
ASE Master Mechanic
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1985 300SD
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2003 Volvo V70
2002 Honda Civic

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