I just finished mine yesterday. Last winter, I used DG501/601, DG105/601 and Collinite 476 on my previous red DD and it got me through a PA winter with ease, on a car parked outside 24/7 in PA. I finally polished it in June, just 'cause I felt guilty. This year, having a freshly polished Black Lacrosse, I did DG105/601, DG111 and Collinite 915. May not go as long as the 476, but the 915 looks so good on Black paint, I can live with it lasting just to March or April. Previous winters, I've used DG alone and Collinite alone, but combining the two seems to make it all but bulletproof.
Bill