Allison Transmission Questions Hi Doug M, Unless there is a tag on your dipstick that says it is Transynde oil, I say it has Dexron in it. Allison dynos all transmissions with Transynde synthetic but it is up to the chassis builder to install their choice and the price difference is usually Dexron. As far as the harsh 5-4 downshift, drive it a while. This transmission has to adapt to the way you drive and it usually takesa couple thousand miles for shifts to smooth out. Thanks and have a great day!