whats the best oil for1,8t

[mike1234]

hi i have a 96 1.8turbo and was wondering if the castrol magnatec oil put in her from audi is any good?because i have been told that these engines have a common problem with the oil sludging up in the oil feed pipe to the turbo.I thought that castrol magnatec was synthetic and this was not a problem.Any help or advice would be apreciated. thanks