MOSCOW, Aug 22 (Reuters) - Urals crude oil differentials remained unchanged on Thursday, though weak margins weighed on the grade's values.
* Traders expected Urals full preliminary loading plan from Russian ports to emerge on Friday.
* Urals refining margins in European refineries remained depressed - at $1.58 per barrel on Thursday compared to $3.45 per barrel on average for the last 365 days, according to Refinitiv Eikon data.
* Trading firm Vitol offered 100,000 tonnes of Urals loading from Primorsk or Ust-Luga ports on Sep. 4-8 at dated Brent minus $0.70 per barrel, but failed to find a buyer.
* At the same time trading firm Trafigura offered a cargo loading from Primorsk on Sep. 1-5 at dated Brent minus $0.10 per barrel, but also failed to find interest.
* Russian state oil major Rosneft has become the main trader of Venezuelan crude, shipping oil to buyers in China and India and helping Caracas offset the loss of traditional dealers who are avoiding it for fear of breaching U.S. sanctions.
* African states like Chad and Cameroon are shaping up to be big winners from new rules to cut sulphur emissions from ships, providing just the right type of oil to produce cleaner fuels. (Reporting by Olga Yagova; editing by David Evans)