Sounds goodCooking oil should be better.
castrol 10w30 for the life of the motorprobably 10w30 should be fine.
i believe factory says use 5w30?the best ting to use is what the factory recommends.
x2i would use 10w30 full synthetic just because he's boosting and it's summer in most places! well even without boosting i would. but on my d17a2 i use 5w20 mobil1 full synthetic. Synthetic is a must for boost!
extremely debatable topic...Synthetic is a must PERIOD.