I just bought a '99 F150 that is in really great shape, but it is in a real need of an oil change, the oil is pure black. I'm wanting to seafoam it, just I didn't know if I should go ahead and do it right now, even though the oil is really dirty, or just give it an oil change now and wait till it's ready for a next one so it's a little cleaner.

 

Do it both ways. Put some in a little bit before you change the oil and drive it for like 30 minutes. It cleans things up in there and all that gunk should come out with your oil. Then once you put your new oil in put some in there to keep things cleaner longer