Hi all im new to this site, thanks for looking. i own a 07 chevy 6500 with a 7.8 isuzu diesel with a allison trans. the trans is acting up only cold not warm. when your at crusing speed 40 to 45 mph it is searching in and out of
overdrive? also when slowing down to a stop under 20 mph the
engine surges. the truck has 219,000 miles and ive done 3 trans services using only factory parts. allison filter with trans synd fluid. is there a additive to use im lost.