Yes you do at least stateside I run amsoil the reason being is regular valvoline Pennzoil castrol and the such does not have enough zinc to protect the cam and flat tappet followers from premature wear and I personally have seen a webcam 218 and a scat w110 wear out in about 15 to 20k miles because of the increased ramp angle they will wear faster especially during initial break in, though improper assembly and adjustment probably didn't help
I run either shell helix or Castro’s gtx in the older engines like this one and penzoil in my rebuilt ones Typically 20/50 in the worn in ones as it’s pretty warm here in oz
