[mitch808]

The N55 is an oil and water cooled turbo, I would personally at the very least change oil sooner than BMW recommends. However, they assume normal driving, and not "race car..."

So that said, following their recommended intervals will work. However conditions that increase the load on the engine/drivetrain would warrant a schedule sooner than normal. This really applies to ANY car.

Living in Chicago, your harsh winter, and sub freezing temps would warrant IMO brake and coolant changes sooner rather than later. Brakes as over time you accumulate moisture in the system, and you want to also make sure your anti-freeze/coolant is performing as expected.

Tow or do a lot of WOT driving, Engine Oil and trans fluid will be changed more often. I've killed a tranny due to not flushing fluid more often (within a year). I had a modded Chevy Suburban, with the crappy 4l60e, and had done a lot of shift/stall work not to mention another 30-50 more ft/lbs, and towing... I lost OD, and only had gears 1-3. If I changed fluid sooner, I would possibly have extended the life of it before a rebuild or upgrade to a 4l80.

With some 15k miles left, and a 5k/yr driving habit, I personally might only do brake fluid, coolant, and top off anything else as needed.