Make sure you buy the woody Wax KIT, it is more, but they also sell just a wax or just a cleaner, the KIT is what you need for your situation, it costs more and is harder to find at times but will work better. I agree 100% with wash it first...don't use dish detergent, infact never use that on a boat, it will haze the gelcoat quick and take the shine out of it. Use a mild boat soap, and like stated above, warm water is best, especially for this job.
Only other option to get it off if it still remains is emry paper, but that will likely leave take some of the shine off the pipework and would not be my recommendation. I would use the woody wax and if needed apply the cleaner twice. Before waxing it, you may not be able to remove 100% of it easily if it has sat really long and been neglected.