Performance Advantages of Multigrade Manual Transmission Oil

To obtain better performance at both low and high temperatures and to improve fuel economy, the performance of an SAE 75W-90 manual transmission gear oil was evaluated in comparison with conventional SAE 90 and SAE 80W gear oils.

Good shift characteristics at low temperatures and reduction of gear noise at high temperatures were obtained with the SAE 75W-90 gear oil.

About 4% improvement in fuel economy can be achieved by using the SAE 75W-90 gear oil compared with an SAE 90 gear oil based on the results of the 10 mode cold-start test.

Tests with a friction-modified oil indicate that further improvement in fuel economy of the multigrade oil can be obtained by the addition of friction modifiers.