an hour and a half?! are you crazy?! an hour at the absolute maximum, but you ARE going to ruin your hair. it will work, but youre gonna be practically drinking leave-in conditioner to get any kind of health to it afterwards.
it wont go green, it will probably go orange/yellow. but that wont matter so much if youre going red. prepare yourself beforehand though, get PLENTY of red hairdye.
i personally use a mixture between Schwartzkopf XXL Live Colour in Real Red, and Directions semi permanent hair colourant in Vermillion and Coral Red.
the directions pots have loads of conditioners in them and really soften your hair. but be warned that if you get your hair wet, like in the rain or something, colour can transfer and run onto clothes.
even if youre using L'oreal, id still recommend getting a pot of the semi permanent colour too. It conditions and colours WITHOUT ruining your hair!
hope this helps!