Ls automatic gearbox oil flush.

[Rs31markie]

Hi all, as title says going to do a flush on the wife's Focus. The oil isn't dirty, but it's ten years old now. I'm trying to decide between penrite or castrol for the gearbox. I use penrite in the engine. Has anyone done this? If so what did you use, did go to Fords but it was totally stupid money, and if using either of those two products I'm sure it'll be fine.