E="dduelin, post: 2284427, member: 4434"]
API CK-4 is no longer certified for use in gasoline engines, not that it matters to the faithful. It was the previous CI series of API certifications that was so good. I ran API CK-4 and SL/SN Rotella 15w40 for more than 70,000 miles in my ST prior to the loss of API certs for spark engines with the change to CK-4.
When they took out the high ppm of zinc & phosphorous in the reformulation of 2016 it just became another oil sold cheap in the automobile and truck aisle. For many years diesel oils like Rotella in 15w40 and 5w40 had the highest ppm of zinc and phosphorus available, good for the flat tappet valve trains in many motorcycles, but not any more. CK-4 limits ppm of the good stuff to 1200 IIRC.
The internal Honda White Paper on oil put to rest the myth that thicker oils run cooler in liquid cooled engines. The study leading to the White Paper's conclusion was that 10w30 in liquid cooled Honda engines produced the coolest oil and cylinder head temperatures. In the good oil days of air cooled engines, thicker multiweight oils with 40 & 50 [running temperature] weight were recommended but a primary advantage of liquid cooling is the ability to tightly control operating temperature and no more than 30 is ever required or recommended for Honda liquid cooled street bikes for the last 15 years. Thicker viscosity oils cause more heat from internal friction and incrementally higher power losses as viscosity increases.
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You need to get out of this conversation ....can't have someone with knowledge and facts spoil the fun