I was wondering, I took a white LED flashlight and shone it into various types of oils. Some of the oils did not glow at all under the light and just seemed to absorb the spectrum. Some other oils actually glowed greenish under the light, reminiscent of the ol Green GC. Is this an indicator of the type of base oil used or is it simply a function of the additive package? Two 0w30s of the same brand were observed: SL did not reflect the color compared to an SM that did. Do you think the reduction of ZDDP for SM required the blender to use some true synthetic base oil?