I like the redline bro, it has transaxle caracteristics, plus has the qualities of most gl-4's
this is from redline.
D4 ATF
Our most popular and versatile ATF, D4 is suitable for use where Dexron III, Dexron II, or Mercon fluids are recommended. D4 ATF is a fully-synthetic product designed to satisfy the improved low-temperature requirements which will be in the new Dexron IV specification, and the improved shear-stability requirements which will be part of the new Mercon specifications.
D4 ATF also provides a GL-4 level of gear protection, making it a superior product for transmissions and transaxles like the Corvette's T-56. The balanced frictional characteristics provide smooth and consistent shifts for extended drain intervals. The superior stability compared to petroleum ATFs allows high-temperature operation without varnishing valves and clutches which leads to transmission failure. It’s stability allows high-temperature operation without varnishing valves and clutches. Also provides improved shifting in cold weather.
this is from a bmw owner
factory with a "lifetime" transmission fluid. BMW does not recommend any service for the transmission fluid because it was designed to last the life of the vehicle. In fact, there is a yellow sticker on the transmission itself by the drain bolt that says the transmission was filled with a lifetime fluid and the fluid does not need to be changed. BMW will not change the fluid for you during any of the scheduled free maintenance visits.
To me, a fluid designated as a "lifetime" fluid from the manufacturer is a fluid that is designed to last the length of my factory warranty. The warranty on my BMW is 4 years or 48,000 miles, whichever comes first. In that scenario, any off-the-shelf transmission fluid will work. In normal day to day driving you can pretty much use any transmission fluid and expect both the transmission and the transmission fluid to last 4 years or 48,000 miles without any service. It's not very good for the transmission, but it will work.
If you want your transmission to last a long time, say around 175,000 to 200,000 miles or more, you have to take care of it. The most effective way to keep your transmission running in top condition is to change the transmission fluid in regular intervals. Your vehicle should have the transmission fluid changed at least every 30,000 miles, more frequently if possible. I change my transmission fluid every 15,000 miles. It's not expensive, it's relatively easy, and it buys me many more miles before the transmission starts giving me trouble.
BMW recommends using Automatic Transmission Fluid in their manual transmissions. Redline D4 ATF is a fully synthetic automatic transmission fluid recommended for the manual transmission in the 325i. It costs about $8 a quart. You will need two quarts for the fluid change because the transmission holds 1.1 quarts. You can save the leftover fluid in the second bottle for the next change if you don't contaminate it, seal the bottle completely, and store the bottle in a cool, dry place. You can find detailed instructions for changing the transmission fluid here.
The difference is AMAZING. After changing from the stock fluid to Redline D4 ATF I could immediately feel a difference in shift quality. This is not something I imagined, it's not something that I just made up, it is 100% real. This fluid WILL make your shifts smoother. The shifter goes in and out of each gate much easier, it feels like it just slips in and out. Even when the engine and transmission are cold the shifter is still very easy and very smooth to shift.
After I installed my UUC Short Shifter it took more effort to shift from gear to gear. Even after a year of constant use it still required more force than a stock shifter to shift. Not much, but the difference was there. After I changed my transmission fluid from stock to Redline the effort required to shift dropped back to stock shifting levels. Ok, maybe not exactly stock, but it definitely made the shifter glide from gate to gate with less effort. It made the shifter feel smoother and creamier.
I can't believe that I drove my 325i for a year and a half before I changed my transmission fluid to Redline. If I had known it would make such a big difference I would have changed to Redline a long, long time ago. It's not difficult to change the transmission fluid and the Redline fluid is relatively inexpensive because you don't need very many bottles. There really is no good reason for anyone not to change their transmission fluid to Redline fluid. Do it and your transmission will thank you.
