Manual transmissions today are becoming similar to automatic transmissions in their complexity. The number of gear ratios is increasing (generally between four and eight) to improve fuel economy and vehicle performance, and their designs are become lighter and more compact. The smaller size of the transmission leads to a reduction in oil capacity which places increased strain on its lubrication performance. For this reason it is recommended to use synthetic oils for towing and 4WD applications.
An increasing number of vehicles are being fitted with DSG or DCT type transmissions which have an automatically operated dual clutch system and are self shifting (similar to an automatic). The operation of these transmissions is computer controlled and relies on numerous sensors providing inputs to the computer in order to make the correct shifts for the conditions.
The most common causes of manual transmission failure are faulty clutch operation, and lack of servicing. Very specialized equipment and technician knowledge is needed to repair a modern manual transmission to the correct standards.