im using the united 1 5w50 and i find it brilliant its a weekend car i have used it for about 500kms now with no problems great cold starts and great oil pressure on idle when warm etc. i had mobil1 5w30 in mine for 2000kms it was sh*t broke down after about 1000kms. they use it in HSV's which are alloy so maybe good for a N/A engine but turbocharged mst heat it up to much and it tends to break down
i Highly Rate the united oils from kingscorp. and i will from no on be buying it in bulk from him. any questions about the oil feel free to contact me