A lot do it on castrol rs, that is why I stopped using it.
Tappets seriously easy to do but long job, cam pulleys off, cams out etc so might as well do cam seals at same time, make sure you use VITON ones as they need to be this because of heat.
I am doing this shortly, as head off.
You can remove the cams without disturbing pulleys but there is a little metal tiny bracket behind each one which can bend, woodruf key also needs pulling to do seals from both cams.
tabetha