The dealer is correct.
The engines VVL is designed to use synthetic oil, And NOT regular dino oil so the valve train will be a lot louder on it than on ester or ester based oils.
The engine is required to run on any full synthetic based oil, What brand? Thats up to you wether you use redline or ester or any other full synthetic.
Please use the search button since there are countless threads on the topic already.
Thank You
