Say I'm in C minor and want to use a VIsus4 chord. Do I use D as my sus4 note? I tried this and got a great, cinematic sound but I'm not sure it's called a sus4 as the interval is not a perfect fourth. Is it?

It seems to my ears that I can use this "augmented sus4" in my chord progs in the same way as a real sus4. Is this true?

Also, I tried using a Db instead of the D and it sounded weird. Maybe because it's not diatonic?