As I've written - the treatment of teak decks has traditionally been scrubbing with salt water. We treat the teak on our little boat and some of our outdoor furniture with a washing and a few coats of teal oil every spring but by the following spring, as a result of natural weathering, the gray begins to emerge blended in with the teak brown. I think a few seasons and silvery gray will be the dominant color. The salt water wash and scrub can only accelerate the process.
"... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
WQJudge