When I polished what use to be our '89 Bigfoot, (with GelGloss), it removed the white chalky stuff, plus dirt, and actually turned more of a mellow yellow, which I figured was more of the original colour. Looks good anyway with the brown striping and decals.
When I first saw the words "mellow yellow", it reminded me of the notice in an old cottage bathroom we use to have; because of lack of water -
"If it's yellow, let it mellow"
"If it's brown, flush it down"
Ok - so that's a different subject