DX engine oil

Currently using 10w40 oil in my 1.8 8v DX engined tin top. The head does seem a little tappety to me even though the head has only recently been put together by a specialist. So that said I've finally managed to find the recommendations in Haynes and it says 15w50.

Is is this what I should give a try? If I understand it correctly 15w50 oil should be a little thicker and potentially quieter then engine

Does your car have hydraulic tappets or shims?

Its the shims. Solid lifters