Things to do to avoid these scams from trading Russian Petroleum Products:

1. Always contact  Moscow embassy in your country's  for help on screening Russian sellers.

2. Possibly ask your embassy to recommend a local lawyer to screen and verify any document that you receive from Moscow .

3. Get your lawyer to invite you to Moscow to verify all documents issued by your seller and to visit your seller.

4. Get the seller to move by issuing PB from reputable Russian Bank with a major Foreign corresponding bank and Vessel Charter Party Agreement verifiable through your lawyer in Moscow .

There is no scam without a Bank. Check the seller's bank listed on the contract. Bank uses their own mail server so if given bank email address shows a different mail server then be concerned. Call the bank. Bank officer should use a land line for their phone number not cell phone
Serious and successful sellers should not have any need to collect Transneft fees upfront from you once you show then preliminary proof of fund via BCL or soft probe. Only scammers want to see your money first, because their business is to collect these fees,not to sell oil. Furthermore, once you send them one payment, they tell you that they have a quota and that you need to send them more deals before they can accept your Pre-advice LC or issue PB.
Even if you ask them to sign a promissory note to return the money in case of non-performance, they will do it because you have no way of collecting that money back from them.
Do not accept any document from these people unless you have a way of verifying it independently. They are master forgeurs for all sort of refinery and government documents.
They use a lot of Seller's mandate all of over the world to bring them business. The Russian mandates are part of the scam but foreign mandates are usually innocent victims who think that they are representing a legitimate Russian seller.
Happy Trading

Please don't be afraid to share your scam stories !!! Scammers use the same scheme over and over because their victims do not speak out
Your story will help weeding out scammers from the business. It is not just about the money, it is about detecting these scams soon enough to avoid wasting time.

NOTE: Since this article was initially posted here, there have been some new company listings on Alibaba.com (Lukhoilsandgas, Golden Oil,....) presenting themselves as mandates for Russian companies like RUSNEFTPROM.

My personal recommendation is not to do business with any mandate or company that lists relationship with Alduke Holdings-Sibneftprom, RUSNEFPROM or any of the companies listed above in this article.

The real test is for you to get a copy of their procedure, they all require upfront fee from the buyer for Transneft fee before they issue PB, POP, or show any oil or SGS report or proof of previous deals where that have actually ship any oil to anybody.