Hey, my 2002 VW Beetle's transmission is slipping. I put the car on the lift and while running i opened the transmission oil bolt and oil was flowing down. The oil was extremely black so i went to an auto part store bought the filter and oil. I ran obd reader and got codes p0740 & p0730. I havent test drove the car but will this help the slippage? Whats the code mean? I know their transmission codes, but what causes this...?