Recreating, preserving weathered siding look

Anyone with experience in trying to replicate the weathered look of old redwood siding, but preserving it from deterioration?

We are trying to decide how to protect the redwood siding on our vacation home on the California coast. It gets a lot of weather in the winter, so the siding deteriorates from cupping, cracking, and continual cycles of rain and sun.
We are trying to preserve the siding, and prefer the naturally weathered, silver appearance of old redwood. We've had some of the siding on the weathered sides redone last year, and some other the year before. The latter walls are now perfect in color so a clear preservative would add some protection (admittedly not as much as a stain, but stains always look too uniform and artificial from what we have seen).

Some of the siding will need to be cleaned before treatment to get rid of black algae stain.

California now requires low VOC paints and stains; right now TWP 1500 looks promising, but we are also looking at Cabot, Olympic, and Superdeck. From reading on the 'net it sounds like the new low VOC formulations do NOT work as well as the original oil-based, high VOC formulas.

Any recommendations, including links to websites that might be helpful, would be much appreciated.