Seems there are some folks that have answered my Volkswagen Tiguan 4Motion questions that have some prior experience. Here's another one. Thanks in advance. 40K mile transmission service, I have purchased the filter/gasket kit from Rock Auto and the specialty fill tube off of ebay. The next question is fluid, the OEM fluid is quite pricey and semi-synthetic it seems. The aftermarket fluids recommended but not certified run the gamut all the way down to $5 a quart for AcDelco fluid. Is this one of those Items I should use the factory fill, upgrade to a 100% synthetic or go for the lowest price. We are talking 6 quarts or so.