For 1998 5 Series Sedan Fourth generation BMW recommends to use: ESSO LT 71141 automatic transmission fluids and genuine OEM automatic transmission fluids with following part numbers: 83229407807, and 83 22 0 026 922. To select the right automatic transmission fluid see the table below.
How much automatic transmission fluid you need to put into 1998 5 Series Sedan depends on the engine installed, and some other conditions listed below.
Without special equipment it is possible to replace only ATF in the AT pan because of the way automatic transmission in 1998 BMW 5 Series Sedan has been designed. It will take about 30–90 minutes depends on your skill level and might save you up to $200 depends on the region you live in.
With a spanner or a retched with the right size head unscrew the refill plug and the drain plug. After that drain old AT fluid. If you want to replace the filter you need to remove the ATF pan, replace the filter and then install the ATF pan back with a new gasket. Screw back the drain plug with a new gasket and refill the transmission with new ATF.
Please be noted that all capacities listed here are approximate. Check fluid levels when adding or refilling as recommended in your 1998 BMW 5 Series Sedan user's manual. Keep in mind that all information here is provided “as is” without any warranty of any kind.
Before doing any DIY service please check your insurance policy and BMW warranty policy for your region. In some regions DIY service may invalidate your warranty.
DIY car service is not as difficult as it looks like and it might save you thousands of dollars per year. It might be even fun and a good thing to do with your kids on a weekend to teach them how basic machinery works. It's really hard to screw something up and damage your car permanently if you use right tools, follow BMW 5 Series Sedan service manual and use right parts and fluids in prescribed amounts. Even modern cars stuffed with electronics can be serviced in your garage or even in your driveway. Changing engine oil, brake fluid, ATF, replacing brake pads, and etc. It's all may be done by yourself in a mater of a couple of hours.
Doing basic service for your 1998 BMW 5 Series Sedan you're not only saving money, but also also improving your technical skills and learning something new.