How often do you service your Auto Trans?

[xQx]

According to BMW, you never have to service your Auto Transmission, they're a sealed unit that should last the life of the car.

According to everyone else - including ZF, who make the gearbox, they should have their fluid changed to increase longevity of components.

But how often?

I always thought it was something you should voluntarily do with your 100,000 km (60k miles) service, which I did - but now my local transmission shop have put a sticker on my window telling me the next service is due in 12 months or 20,000 kms. To me, that seems vastly more often than I'd expect - especially given it went 100,000km before it was first serviced.

I don't blame mechanics for erring on the side of caution (especially when it means more business for them) - but what's the 1addicts expert opinion?

[desertman123]

20,000 km for trans service? Please lol. They're just trying to cash out.

Engine oil sees combustion byproducts and moisture, so frequent changes are understandable. But the trans sees only very very small amounts of moisture and zero combustion.

I've always heard 100k-160k km (60k-100k mi) is the range you should swap fluid and filter. Just a drain and fill, never do a flush.

[1and1]

For a 135 that's used as an aggressive daily driver I'd say 60k miles is good. If you're doing hard core track days or drag strip you may wish to change more frequently.

Remember that solenoids should be done around 100-120k miles for basic daily driver and, again, more frequently for harsher environments

[xQx]

Thanks, yeah. That's what I thought.