Is there a way to tell what type of engine oil you have inside your engine by looking at the colour or something?

Mineral or Synthetic?

My Service Agent said they either put in Castrol GTX3 (mineral) or Valvoline ProBlend (synthetic)

no

if you can get a good smell of it mineral and synthetic have 2 different smells the mineral has a stronger oily smell the synthetic has a cleaner oil smell in my eb xr6 i use penrite 15w-60 semi-synth