I wouldn't use gunk unless there was really no alternative to gum and varnish buildup. Recently though, I used it in a car I bought last May - this car had been sitting for 9 years. When the car got hot, a lifter would stick - varnish is my guess. Anyway, used as directed - no more sticky lifters. Afterward, I find that Gunk is basically diesel fuel.
Just change your oil on a regular basis and let it drain out well. When you drain it, you want it warm but not really hot - when hot, it is too thin to carry any crap out with it. Pull the plug - go make coffee - come back in 20 minutes or so. And, fill the filter with oil before you install it.
HTH