I did the research but couldn't find the best answer so i think maybe i'll post my question. I'm thinking of getting an oil change from some local shop. I'm thinkin of getting mobil 1 synthetic oil 5w30, how is it compare to castrol which bmw recommended? and how much do I need? i saw someone said about 6.9 qt, so that's around 6.5 liters? is that enough for a V8? and has anyone tried the pennzoil fuel system cleaner and injector cleaner? does it do any good? i read some review and everyone say it make a significant difference.

thanks again fellows for the best forum on Earth

 

Mobil 1 5w30 does not meet BMW LL98/01 requirements, but the 5w40 grade does. Always check the back of the bottle for the BMW endorsement to be sure. 5w40 is allowed in my engine (I6), and Mobil1 5w40 meets these requirements, make sure 5w40 it's OK for your V8, (your manual will tell you).
If you want to stick to 5w30 then go for Castrol Syntec. There are others like Motul and Total which are excellent but I don't know if you have access to those where you live.