2005 BCA Judging standards say no deduction of points for differing shades of the correct color. P 13 Judging the engine.I tried some and it is not even close. Maybe if the whole engine is painted and looked at under the shade of the hood and parked away from some correct ones, it might pass...
Different brands may have a tint different than the one I tried. You will be closer to correct buying from a Buick vendor (but it will not be $8 ).
The lighter color looks like Pontiac used in the 60'sLeft is repainted breather with paint from Buick supplier years ago on a driven car. Under the orange decal about the same. Fresh can from same supplier shows fresh head bolt which I like. Bolt next to it fresh Duplicolor which is lighter. View attachment 8984Breather on far tight from a tired motor that needs rebuilt. Guess paint the whole thing at once and see what happens...