15w-40 engine oil for hydrulics

I'm going to change my hydraulic oil from hydraulic 46 that's in it now, to 15w-40 engine oil.

But am not sure if it should be engine oil meant for diesel or petrol? or if it matters at all.
my understanding is that there is different additives in different types and brands.

Does anyone know if it matters or have a recommendation?

It's for my PC30mr-1, Komatsu can't tell me.