MIL-L-23699 OR MIL-L-7808 hydraulic oil

[rQuestionEngineering]

What is the different between MIL-L-23699 vs MIL-L-7808 hydraulic oil ?

What are the example brands for each ?

Why a mixture of hydraulic oil may cause damage to the actuator ?

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[TugboatEng]

Viscosity is the primary difference.

What type of damage did the actuator experience and could this damage be caused by incorrect viscosity?