ok barring all flaming and stupid happenings...

since you're going for realism... i just did an oil change and I think that the raw metal is a little too dark, sleek and shiny. its pretty right now, but realistically it should appear a little less polished and a tad lighter (in value) in my opinion.

also, the interior of the oil filter contains a filter element doodadd, you might either model that so that it looks not so empty in there, or darken the interior so that the green exterior does not show through the holes. looking good though, really like the painted metal exterior. those were just my observations that were instant gotchas on it being a cg image.