Generally, no, the brand of fluid you use does not matter that much. The one thing that really matters is the type of fluid you use. For example, if you drive a Ford that requires MERCON III fluid, then you must use a fluid that meets the MERCON requirements. Using a fluid that does not meet the requirements of your transmission will cause problems and potential damage to your transmission. There are many different brands available that meet the requirements of modern cars, although some brands tend to be better than others. If you want the best transmission fluid available, then use one of the fluids from the list in this article.