Hi Tangent,

Why not consider Delo-400 which is rated at 15W-40 and is virtualy identical to the Delvac, except being ISOSYNTH, it remains stable for longer drains and resists high temperature breakdown quite well. It is also rated at CI-4 so will keep the internals of your engine quite clean.

Being a previous die hard Delvac user, I am quite pleased with the change. In fact Delo-400 meets the million mile warranty from manufacturers like Cummins etc.