I reduced the epoxy primer to use as a sealer. After checking with a friend (been painting since 15 including owning and painting in his own auto body shop), paint supply store and them checking with another store and two of their customers can't figure out how it is happening on individual panels all prepared and painted the same and at the same time. I have the hood and tailgate removed, grease and wax remover (2 times, wiping when still wet) then sanded and used grease and wax remover again. Everyone recommended not using a sealer, just repaint. Today I shot SS urethane. Has the paint shop mix as color as close as they could color match to the windshield frame and dash (both have not yellowed). Has a nice gloss and reflection (compared to SS enamel) but was only a hour old. May have to wait a couple months to see if it tries to yellow again. I'm hoping my friend is correct that I may have not mixed the gallon enough to completely mix the pigment. The yellow can settle toward the bottom. As I used the gallon (couple different paintings) I may have been going a little more yellower (dirtier white) with each painting (3 paintings). Still doesn't explain the difference of the parts and the tub and why you can rub it out and the color was close, come back 7 mths later and it's darker. Hope this works.