I'm trying to decied if synthetic tranny fluid is worth the money or not. I have a 2500 HD 4X4 stock with 75000 miles. I don't know if the tranny has ever been taken care of. Thts the problem when you buy used.

 

I bought my 2500 series new, serviced transmission at 60K then had to have torque converter replaced at 80K.

If it were me, I would use the oil called for by the manufacture. You are talking some big time money, if you have to do a total rebuild on one of these heavy duty transmissions.

just my 2 cents,

but I have been there, am sure you have the 4L80E transmission, should have 17 pan bolts.

 

Change the fluid in it and add a pint of the lucas transmission treatment to control heat and lubricate the valves.