IMO, and I'm new at this as well, so please, wait for a shark to answer, oil, sludge, parasites, and just plain not knowing what is in there would more than likely have a detrimental effect on your tank. Maybe if you went offshore about 25 miles, and used scuba gear to dive down and get some sand, that may be okay, but still "iffy" IMHO. Are you just setting up a tank? If so, there are less expensive options to buying live sand, such as southdown playsand with a detrivore starter, or even if you know someone who has a tank, get a scoop of sand from that tank to "seed" your sandbed. Also, the lr will put any critters in it that you may need. Other than that, it's a waiting game for the bacteria to multiply. With all the time and effort we put into our tanks, I wouldn't want to put something in there that may damage the lr, ls, or any inverts, fish, etc. As Broomer5 says, your tank...your choice...but I think you'd be dissappointed in the strength and solidness of your tank.
Good luck