I'm using Delo 15w40 only as we speak for my rebuilt 6.0 lq4 going back in the 04 below.
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04 2500hd 6.0 258k(: Delo 15w40mix XG3675 VML ATF,PGL
03 C7500 Dmax7.8l 128k Delo 15w40,M1ATF,Dexcool
06 2500hd 6.0 181k T5 10w30 PL25288 ST DexVI,PGL