93 mgm trans shudder

it has 110,000 miles on it ,trans rebuilt 6 years ago ,the car sat the last year and half ,shifts real good ,but when it goes from 3rd. to o.d i get a shuuder .is there a good additive i can use.i heard it might be the t.q..and it doesn,t always do it.
thanks
bob

Trans medic makes an anti shudder fluid that works well. Just ask your local parts house for shudder guard.

well i used it .and its almost gone ,would it hurt to put another one in
thanks
bob

I would change the fluid and filter and add another bottle. It may be beneficial to drain the torque converter and get all the old fluid out. You will need about 12 quarts to change all the fluid.

should i use regular fluid or go for that mecron 5 fluid.
thanks
bob

You can use either. You can use mercon 5 in mercon fluid, but you can not use mercon in mercon 5 systems. Make any sense?