You need to find a different oil. You need a Cat safe oil. The high zinc content in that oil is hard on the Cats. No matter how well your rings are sealed there will be some oil migration into the exhaust system. I don’t know if Lucas makes a Cat safe oil but you should find one. I know I killed several Cats on early 2000’s GM garbage and it was quick because those things had horrible ring seal.
Hi 448Scamp this is the catch 22, I been trying to figure out what oil will have enough zinc for the 520 lift cam but not too much where it will be problematic for the cats, maybe someone can provide a recommendation.