We too put saltillo tile throughout the house. Using a product made for saltillo tiles, we sealed the tiles before placing them, sealed again before grouting, then 2 more coats after grouting and followed with 2-3 coats of a finsh sealer. Looks great, but greasy or oily spills stain, leaving a dark spot. We've tried everything to clean, and haven't found a solution. Is there a way to remove these stains, and is there a way to better seal the tile to prevent further damage?