Something that seems to confuse people about muti-viscosity oils is th numbering system. Example-10W30. This oil is essentially a 30 weight oil that has the flow properies of a 10 weight oil at 32 degrees F/0 degrees C. thw "W" in the gradinf stands for "winter". Most think that it means "weight".
I do believe that the 216/235/261 engines seem to run happier with a single grade 30 weight just from my own experience. Especially if they have had performance modifications.
