As you will see by looking at the bottle of Delo, It has two API ratings. SJ and CH-4. For those of you who are unfarmiliar with the API ratings system, The first letter of the rating classifies the type engine the oil is certified for, in this case, S = Spark ignition and C = Compression ignition. Basically, a C- rating means its a diesel oil, S- means the oil is OK for gasoline, Propane, and CNG.
Since Delo carries both (along with every diesel oil out there) it is OK to use in a gasoline engine, and usually preferred because it is derived from higher quality petroleum basestocks when compared to regular gasoline engine oils that only carry the SJ rating.
The delo will keep your gasoline engine running happy, and I wouldnt recommend anything else for your 420. It would be my first choice if I ran dino oil, but all my vehicles get Mobil Delvac-1, simply the finest synthetic oil available in the US.