As long as your oil light goes out when you start your car, then your oil pressure should be fine. Im not sure what the specs are on oil pressure. The rattle you here on start is typical BMW v-8 chain rattle. This can be cured most of the time by changing the main timing chain tensioner. You can get it for about $60 and takes less then 30 mins to change. The DIY can be found on this site. I changed mine and it cured about 90% of my rattle on start. The other 10% I cure with 1 bottle of Lucus oil additive at oil changes. A lot of people have given me $hit on this site for doing so, but I have zero chain rattle when I use it.
Last edited by JasonSC540ia; 01-24-2013 at 02:19 AM.