I am a 12 year long truck and large school bus driver. They recently assigned me an 18 year old International Bluebird diesel bus with inline 6 cyl and automatic tranny. I think its an Allison 5 speed type. The bus has nearly 300K kilometres (about 180K miles) of urban and highway driving. Shifts were very rough at times with a loud woomph changing gears at times. Very noticeable and no doubt tough on the Universal joints etc drivetrain wise. So I grabbed a 24 ounce narrow tip squeeze bottle [Lucas Transmission Fix] and pushed the full amount. Shifts are not like a brand new bus but noticeably quieter and less shocking. Got better real quick after use. -Mike G., Aurora Ontario Canada