make sure you don't have serious sludge built up in the derailleur pulleys. be sure the chain is seriously clean. You know it's clean when you change cleaning solutions and new the chain doesn't get the new solution dirty (assuming you're removing the chain to clean it). You also might want to try a thicker oil, the kind that's typically sold as a "Wet" lube. The upside is they quiet a chain better than a thinner type. Wax dissolved in solvent that evaporates is something a lot of people like but it can be noisy and I'm not a fan. Thicker oils like Phil Wood Tenacious oil can be challenging to get in the rollers but after oiling well the key is to wiping clean. If you really get anal about cleaning the oil off the outer part of the chain, the chain won't pick up dirt and will remain clean and as noise free as you can get.