I'm surprised that they put Mobil Delvac in your gas engine car. It will do quite well in a gas engine car, but it is unusual to see this done. The Delvac and Delvac One are fall in a catagory called "Universal Grade". This oil is designed with more cleaning additives and detergents to disperse the soot in a diesel engine, thus they are designed for Diesel engines.
They work quite well in gas engines because of the additional cleaning additives. But most shops or service departments would not use this in a gas engine unless it were specified.
I use Delo, the Chevron equivalent to Delvac, in most everything I own, gas or diesel. I have taken apart some of these engines that have lived their life with it. The gas engines are spotlessly clean. The diesels are very clean too except in a different way because their diesels they have black oil in them.
In summary, Delvac is about as good as you can get in the way of Dino oil, Mobil One would be better but considerably more expensive.
Have a great day,