Did you keep some pieces of the Trex when they installed it? If so, stain the spare and try ammonia on it. Ammonia combines with oil to form soapy stuff that can be washed off.

I have used a product called Corte Clean to clean grease and oil from my BBQ. It did a GREAT job and cleaned my deck to look like new. I highly recommend it and it is eco friendly. Best of all it did not smell like ammonia or any nausious chemical.

I used corte clean eco friendly composite deck cleaner that is recommended on the TREX web site @ http://www.trex.com/Universal/faq_care.asp after reading about it.

It did a far better job than any of the other chemicals I have tried including bleach and toxic deck cleaners from Home Depot. My Trex deck almost looks new.

I wish I would have used this stuff before the bleach that others recommended. The bleach greatly faded my brown Trex deck and caused rust stains around my screws causing another cleaning issue. It also killed the plants surrounding my deck. Thankfully, the corte clean brought back some of the color and removed the rust stains in addition to the many new mold spots that appeared.

I just used the Corte-clean on my 2 year old Trex deck. When mixed as directed (1 1/2 cups product/gallon of hot water) the stuff was useless. When mixed at nearly double that strength, it was an effortless job. Problem is, as a first time user, I believed their square foot estimates for coverage. Halve the estimate and double the product strength for an easy job removing those leopard spots. Oh--and rinse it well--the product turns white if you don't.

Halve the estimate and double the product strength for an easy job removing those leopard spots.

What ARE those spots???? (And thanks for the tip on that product!)

those spots are mildew. We clean our Trex yearly with a bleach based cleaner from HomeDepot (Behr brand I think). Comes out looking like new.

As for the OPs problem -- I am not sure anything could remove that.

If I am reading the MSDS on Corte-clean correctly, the active ingredients appear to be generic Oxyclean and TSP substitute.

I tried the Behr product from Home Depot to clean my three year old Trex deck of black mold spots and other stains, without success. I then tried the Oxy Clean when the Home Depot Behr product failed. Finally, I called Trex and they recommended to Corte-Clean product. I tried it the following weekend. Success at last! I wish I had not wasted a weekend and so much money on the other products. I guess this is why Trex recommends the Corte Clean product and not the other two. Lesson learned. I hope my post saves other Trex owners from wasting time and money as I stupidly did.

I used Corte Clean on my Trex deck at maximum strength (2.5 cups per gallon of water), twice in one day. I scrubbed it thoroughly and let it sit on the deck for 45 minutes each time before rinsing. Although it looks better, Corte Clean did not remove all of the dirt, mold and mildew. At $42 for a 6 lb. container it should perform as advertised and I should not have an aching back after using it. I'm going back to bleach and detergent which worked better and cost much less. I'll still have the sore back, but my deck will be cleaner.

Steve I had the same experience with corte-clean . Scrub and still not satisfied with results. I also have a problem with white residue /staining left behind on the decks wood framing.

I don't know how to get rid of that stain but for mold, fertilizer stains from my pots and reg stains my handy man removed them a with a small power washer, no cleaner. It made the deck look like new. I have found one for $100 and am going to buy it.

Have you tried 30 Seconds Cleaner? We've used it on our deck and it worked great. You can check it out at 30secondscleaners.com I've also seen it at Home Depot.

We used Corte Clean to clean our Timbertech composite deck. It left a white chalky residue. I called the Timbertech who suggested that we wash the deck with Dawn. That helped a little. But then we mopped it with a vinegar and water solution....looks brand new!