Ryan,
A year of weathering on PTP should be plenty of time. Unless the wood was full out shaded from the sun and/or protected from moisture.
I'm not familiar with Sikkens but if it is mostly oil based, you may want to try acetone. Take a rag, douse it with some acetone, and quickly try rubbing out a small "shiner". The stuff is extremely volatile and evaporates quickly.
A note of caution. Don't light a smoke when working with acetone.