Quote Originally Posted by 2manymustangs View Post
My buddies at the shop here do SWEAR by the synthetic for these big slipNgrips... THey say that there is no doubt about the increase in hard parts life with the full synthetic on high high mileage transmissions...

Most of their work is on trash trucks with a BAZILLION miles on them... THese little 1000s are about 1/3 the diameter for the frictions/steels/torque converters...
Transynd is the way to go with the Allison. From cooler operating temps, to 100K miles in between changes in normal conditions, and even like 50,000 miles in severe conditions, like your trash trucks. Those were always a shop favorite.

To get an idea the abuse that a trash truck takes, you just have to watch one run down the road... they idle, then WFO to the next can, idle, then WFO all over again. Not to mention all the trash and debris that gets packed around the transmissions and in the coolers. Those things take a licking!