Steering clutch case oil komatsu D41s3

My loader left steering clutch works great when cold, as it warms up and the fluid gets hot it begins to quit releasing. The brake bands are adjusted to spec. My guess is the throwout cylinder is leaking a bit. The manual calls for straight sae 10wt in the case. The oil is dirty, I am changing it for the first time since I bought the machine. Can you run a multi viscosity oil such as 10w30? Thinking the heavier weight when warm may help with the throwout problem. Thoughts?

Do to necessity I put sae 30 in the case, loader ran great the while time. Yay!

Now to find the hydro leak