Outdoor Douglas Fir, need help with...

I used Douglas Fir to build a playset. I was told by alot of folks that if I treat it with a good wood preservative it should last a long time. You must remember this is not treated Douglas Fir. I used Olympic Tinted Sealer to seal it and it looked great for a few months and now its getting gray and streaky and simply put it looks bad. So was I misled in using Douglas Fir? What if I strip the stain and apply a Semi-Transparent Stain? Or shoud I start replacing boards with PT lumber? I was shying away from treated lumber due to the heavy metal content. I was not finding alternatives around here so I went with fir. Cedar was a ton more money and I simply don't like working with it. I did use it for some of the side rails though and they look good yet. So please share your thoughts and advice.

Doug Fir is not a good wood for exposure to weather. I would have have used Redwood or Alaska Yellow Cedar. I realize your concern about cost, but if you want wood that will look good after exposure to weather, you pay the price.

A lot has to do with the grade of wood. Most likely you got something like "#2 or better", a typical construction grade. For outdoor decks, select quarter sawn fir would have been more appropriate. It would still need sealing, and is probably not the best choice for outdoor projects.