Chevron/Havoline, Pennzoil, Citgo HM 10W-40's are all about 15.5 cSt @ 100C vs the 14-15 cSt for a standard 10W-40.
Maxlife HM is probably another option , but I don't have a data sheet close at hand.
What are you looking for, Jelly, the higher viscosity or the seal conditioners?