Cheers for that mate I'll give the app a try later and go for full tanks in the race today.@Sean Rogers Yup, unfortunately AC lacks features in that department, but, fortunately there is an app that makes your life a little bit easier! - http://www.racedepartment.com/downloads/pitconfig.8032/
You can preset your stop and you just come into pits (easy and simple).
As for the race, I don't think that we need to pit, M will hold on pretty well.