Is it normal for a C2500 to require adding oil very often?
My C2500 has 78000 original miles. 5.7L V8.
This truck was owned by my dad who bought it from some people who only used it to tow a boat. he put about 55000 miles on it before I got it. He always kept several quarts of 10w40 or SAE 40 in the truck and had to add oil to it all the time. How much I don't remember and can't ask him as he passed away several years ago. I use SAE 30 as I live in Phoenix, AZ.

It is not my daily but recently I drove it several times over the course of a couple of weeks and had to add 1 quart during that time. When I moved him from Seattle to Phoenix I drove it around Seattle for 3 weeks and in that time had to add 1 or 2 quarts.

There are no oil drips. When I start it there is some greyish blue smoke that comes out, though not as bad since I had the fuel pressure regulator rebuilt. It does not smoke (that I can see) once it's running.