While you can expect to face some minor "break in" period with piston valve instruments, the degree of severity that you describe facing shouldn't be expected "out of the box". Nonetheless, you may discover that playing it for several days or a week with the right oil may result in a dramatic improvement.
Still, continuing reports of this sort always make me wonder about the statements vendors make about play-testing instruments before shipping and about their continuing policy/habit of shipping instruments that just haven't been cleaned in any reasonable way. At the very least, they should stop claiming play-testing if they don't really do it, and they should include a clear statement in big red letters that you need to thoroughly clean the instrument before using it -- and include specific instructions of how to do it. Certainly most customers don't expect to have to pay for a professional cleaning in order just to play their new instrument.
So what's the "right oil". Well, in my experience with these Chinese instruments, the valves are very tight on them -- which is actually a good thing if not overdone. So you want a thin valve oil. I use Yamaha Light (not the Regular or Vintage) Synthetic Valve oil. But others prefer different oils. And some prefer non-synthetic ). If you've cleaned it thoroughly (detergent, flushing repeatedly through the valve section to be sure you've got everything out of there), then apply your thin oil and play it for several days, and see how it goes before returning it. The best way to do this is to pull the tuning slide and power rinse the instrument from the mouthpipe. (I actually built a dedicated apparatus for cleaning my tubas and euphs in this way.)
If you want a thin valve oil specifically for this purpose before you decide on your long term choice and happen to have any ultra-pure lamp oil, just use that. It's simply highly refined kerosene. While you can get it at hardware stores, Walmart, etc., going out and buying a bottle of it will cost you as much as buying a decent brand of thin genuine valve oil from Amazon. But if you have some lying around, it would be a way to go -- if you don't object to the slight kerosene smell and taste. Then, of course, reclean the instrument thoroughly again.
Another thing you might try -- just as a test -- is to use soap and water as the valve lubricant. This won't last long, but if you put a soapy water solution on your valves (or dip them in it), and then see how they work, this could be very telling (also, you're again cleaning the valves by doing this). If the valves are sticky and hard to move when you try this a couple of times with the soap-water lubrication, that points in the direction of a honing or break-in problem at the factory, and probably not something you want to be responsible for yourself. But otherwise, if by a good cleaning (just by you instead of investing in a "professional" one at this point), and thin valve oil, you can get it to work to your initial satisfaction, then it's better to go in that direction instead of going through the hassle of returning it and starting all over with another.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)