FTSE 100 engineering giant GKN was providing a lift to the automobiles and parts sector today after an upgrade from Credit Suisse.The Swiss broker raised its rating from neutral to outperform saying that following the 11% share price fall over the last month, any concerns surrounding the rumoured acquisition of aircraft engine group Volvo Aero are now discounted in the current price. "There is no certainty that GKN will acquire Volvo Aero Engines but with MTU [MTU Aero Engines Holding] having now reportedly exited the bidding process GKN is in pole position," the broker said. Shares were up around 5% today.Despite being the only stock in the sector making gains, the heavyweight stock has enough clout to lift the category up 4.7%.Leading the downside today were the oil and gas producers after a one-by-10 mile oil sheen was found in the Gulf of Mexico.While the source of the sheen is still unknown, it is located between Royal Dutch Shell's Mars and Ursa projects which has prompted the firm to send out an 'Oil Spill Response Vessel'."A thorough inspection to date of Shell assets reveals operations in the area are normal with no sign of leaks. We have also confirmed there are no well control issues associated with our drilling operations in the area," Shell said. Despite the assurance, shares had fallen steeply in early trading, recovering slightly to trade down 1.2% late on.BP, Solo Oil and JKX Oil and Gas were also registering losses.Top performing sectors so far todayAutomobiles & Parts 4,687.82 +4.70%Chemicals 8,309.22 +2.85%Mining 20,115.37 +2.70%Personal Goods 24,304.45 +2.68%Fixed Line Telecommunications 2,486.30 +2.32%Bottom performing sectors so far todayOil & Gas Producers 8,120.05 -0.69%Health Care Equipment & Services 3,457.01 -0.39%Mobile Telecommunications 3,911.94 -0.35%Equity Investment Instruments 5,673.51 -0.09%Gas, Water & Multiutilities 4,899.47 -0.04%BC