The Mobil 1 is very good stuff, a true pao synthetic. But thye 15w is not the best cold start protection, 10w would be better as it would circulate faster.

There is better in terms of quality to, the ester based synthetics have the edge on pao synthetics.

Also there is price, an oil like the Silkolene Pro S 10w-50 is better abd cheaper then the Mobil 1.

Cheers

Guy.