35D owners: How often do you refill def?

[11_335D]

I have a 2014 x5 35D that I purchased with 124k miles in nov 2017, I now have 141k miles and the DEF low warning hasn't come in yet. Should I be concerned? I've only changed out the fuel filter and oil since ownership. It hasn't gone through any service that would top off the fluid at the BMW dealership. So my question to those who own the 35D, is this normal? I do commute 35 miles each way to work 95% hwy 5% city ~70mph avg 33-34mpg if that matters.

[Mr.47]

It all depends on how much you drive, and idle.

My commute is roughly 800 mi/month @ 60% highway/40% city, and my def goes down about 5% every month in the Passive tank (4 gallons) using ISTA/D to read out the level, so roughly 9-10 months is when I have to refill the passive tank with 2.5 gallon + 2L bottles, and it be exactly 12 months for when both active and passive tank to run dry, however I usually wont let it run dry, I refill DEF every oil change (@ 7500 mi) and before winter.

Note that it should be a habit to refill/topoff the DEF during fall and before winter, to reduce the chance for def to freeze up in the Passive and Active tank.

[11_335D]

I drive quite a bit I would say ~25k/yr mainly highway hardly idling. I wish there was an Idrive level readout but I guess I need to get onboard with this ISTA/D stuff. thank you for the info.

[MrTookies]

Originally Posted by 11_335D

I drive quite a bit I would say ~25k/yr mainly highway hardly idling. I wish there was an Idrive level readout but I guess I need to get onboard with this ISTA/D stuff. thank you for the info.

DEF Fluid refill has been for me about every 7-10k. With that being said after the first couple of times I just made it a habit and waited for "1000/mile left" signal and stopped at Walmart or wherever you buy yours from and refilled with a 2.5Gallon Jug.

That way I never have any standing around in a hot/cold garage. Seem to work just fine.

Alternatively just top it off when you do your oil change.

[MotoWPK]

I have my DEF topped up at every oil change and have kept track of the volume added and miles driven since new. Over ~63K miles it works out to about a 20K mile range to empty.

If your DEF consumption is similar, it's quite possible that if topped up shortly before buying your X5 at 124K miles it hasn't run low by 141K miles.