Hello XXXXXXXX,
I hate to tell you but you have the wrong fluid in the trans, this is not helping you at all, only hurting you. Also the fluid level was probably not filled properly as well. The level needs to checked when the trans is cold and the engine running for your info. Try this first and let me know what you find.

After your car has sat the 4 hours open the oil filter housing and check to verify that it is full of oil if not, you may need a new housing. This clatter at start up is not a huge issue, somewhat normal. But check the housing and get back to me, we will go from there.

Yes there are check valves in the housing to keep the filter housing full of oil so that the engine doesn't have to fill the housing first reducing the time that the engine gets oil pressure. How does the O-ring on the filter housing cap look? What is this rislone stuff anyway, if it has any hard partilces like PTFE or graphite this may plug the check valves or worse start causing your valve lifter to bled down and cause engine clatter on first start up. This may also be your problem and the only way to verify this is to remove the valve covers and check the valve lifter themselves. This is not a huge issue for the 1-2 seconds that you mention just loud and annoying. If it gets louder or longer then it is time to do something for sure. These engines are very well built and farely long last so oil additives really aren't necassary, especially when using high quality synthetic oils like Castrol(bmw's oil) or Mobil1.

If there is not any oil at the lip of the housing when it is first opened the filter housing is draining out. More than likely one of your oil line check valves are stuck open the housing is loosing its prime and the engine is running with out oil for a second. I would stay away from the oil additives as most of these products were developed for domestic engines with much looser tolerances than your engine, and the good quality oils such as the ones you are using this rislone stuff is really uncalled for and may even be detriment to your seals. As for the fix I would install a new oil filter housing along with new mounts.