Thank you all for suggestions. I looked at this form 550 but it really does not apply to me as a U.S. non-resident alien. To be honest, I really feel sorry for you, U.S. citizens, for having to deal with such a complicated tax system. It should be much simpler and the fact that you need to pay U.S. taxes on your non-U.S. income even if you do not live in the U.S. is a good reason to start a revolution - but that is politics...
I agree that selling an asset for below its market value, especially to a connected party, would be tax evasion, even in my country. However, I have got something better:
It came to my mind during sleep - use calendar spreads on CL futures!
Go short Jan, long Feb. Wait for it to develop - let's say it is the long Feb leg that shows the desired level of loss. Close this leg and AT THE SAME TIME go long Mar to keep the net position (short Jan - long Mar) at no directional exposure. Then, in new tax year - close out both legs.
It seems perfectly legal to me and no court, no tax official, no logically thinking person could question it. It is also not without risks and costs - the main being: cost of spread, imperfect execution, commissions, risk of spread going against you which will cause a "real" loss of cash.
What do you think about this idea? What can go wrong with it? Does every FCM accept reduced margin on calendar spreads?