Does changing your differential fluids help your transmission

HI, The transmission and differential assembly are two different devices that are linked by the drive shaft. Now; if your vehicle is front wheel drive only, you do not need to change your differential fluid because you wouldn't have one in that case. With that said; Changing the differential fluid will not affect your transmission. It will only provide better differential lubrication and functionality. Administering a flushing technique to both devices will only have an individual effect on both devices.

NOTE_ Differential maintenance is quite rare for the average city driver. Your transmission will require more attention than most differential assemblies. Now; if you do a lot of off-roading and pull heavy loads on the regular, i would have the differential assembly inspected every 16k. If not, simply, have the transmission checked every 10k for proper fluid and filter change.