I replaced my bucket tappets on my M104 becuase of noise on start up and it did not solve the problem. I suspect there may be a check valve somewhere in the motor that keeps the oil from flowing out of the tappets and, in my case, the oil leaks by this valve. I've owned SAABs with the 16Valve motors that have bucket tappets as well and they all had noise on start up too. It began around 100K miles but the motors ran well until I sold them with over 200K.

I wish I had not wasted my time & money replacing them on the M104 - It is most quiet with Mobil1 0-40, so I stick with it. With Mobil1 50-30, it was either really quiet or really, really loud. I suspect becuase it either held in the buckets (quiet) or leaked down (loud) and took a while to prime 'cause its really goopy stuff.