[mefferso]

The last time my DEF tank was re-filled was at the dealer when they replaced my tank. Out of curiosity, I haven't filled it since then and thought I'd go until the low DEF warning required me to to see how many miles I could get out of that tank. Just wondering if anyone else has done this and what would be typical. I do drive on the interstate about 75% of the time. I'd be super happy if I can make it to 20k miles since I do oil changes very 10k. Of course the "must fill in 999 miles" warning will probably come on today since I posted this thread.

[135i_vs_]

If you had an oil change at the dealer within the 17k, they top off the DEF tanks..

[mefferso]

Originally Posted by 135i_vs_

If you had an oil change at the dealer within the 17k, they top off the DEF tanks..

I do my own oil changes. Last one was at 50k. They changed the DEF tank and filled it up at 42k and my current mileage is 58,998 miles.

[Hoooper]

Do you have an EGR block? I have mine blocked, I kind of expected to be filling DEF more often, but Im sure I havent put in more than 10 gallons over the course of 50k miles. I put in 2.5 gallons last time the light came on and that has to have been 10k miles ago if not more . Maybe the NOx sensors are going bad and have drifted to the point where they are indicating so much less NOx than actual that the DEF injection is significantly lower. If thats the case I will know once they drift out of acceptable range I guess

[mefferso]

I bought the car used as a CPO with 33k miles on it. Only visible mod then was a VAC module. I suppose its possible to have a block but it wasn't from me (but forthcoming). Wouldn't a SES light come on if I had one?

I guess that's possible with the NOx sensors. Fine with me if thats the case. Less money to spend on DEF.

[eurojulien]

My dealer replaced my SCR tank but didn't refill it because "it wasn't covered" so they just refilled it with what the could form the old tank *sigh*


light came on yesterday, put 2.5 gallons in already, need to get more.

[WreckerX5d]

Mine's been pretty consistent at filling it up between oil changes. I have 90k miles.

[kbsilver]

Originally Posted by mefferso

I'd be super happy if I can make it to 20k miles since I do oil changes very 10k. Of course the "must fill in 999 miles" warning will probably come on today since I posted this thread.

Pretty much the same as my plan now that I am out of free maintenance. Oil changes every 9K-10K miles, DEF fill on demand. Think I will let it get down to 500 miles to no start then put in 5 gallons (2 jugs). This is with the thinking it's a good idea to try and get out as much of the older DEF as possible before filling.

[montr]

Originally Posted by kbsilver

Pretty much the same as my plan now that I am out of free maintenance. Oil changes every 9K-10K miles, DEF fill on demand. Think I will let it get down to 500 miles to no start then put in 5 gallons (2 jugs). This is with the thinking it's a good idea to try and get out as much of the older DEF as possible before filling.

I also think that it is better to use most of the DEF in the tank before refilling. Initially BMW procedure was to drain all old DEF prior refilling at every oil change (every one year or less). The DEF has a shelf life of 1 year. Now, he BMW procedure is to not drain the old DEF before refilling (cost saving?).

I do the same as you except that I do it with 2.5 gals at a time. Also, it is important not to overfill as stated in SI B16 02 10.

[kbsilver]

Originally Posted by montr

I also think that it is better to use most of the DEF in the tank before refilling. Initially BMW procedure was to drain all old DEF prior refilling at every oil change (every one year or less). The DEF has a shelf life of 1 year. Now, he BMW procedure is to not drain the old DEF before refilling (cost saving?).

I do the same as you except that I do it with 2.5 gals at a time. Also, it is important not to overfill as stated in SI B16 02 10.

Does the E90 really only hold 5.3 gallons of DEF? Thought it was more than that. Hmmm. Do you just dump the whole 2.5 gallons in to the passive and let the pump do the rest? That would actually be pretty easy.

[montr]

Originally Posted by kbsilver

Does the E90 really only hold 5.3 gallons of DEF? Thought it was more than that. Hmmm. Do you just dump the whole 2.5 gallons in to the passive and let the pump do the rest? That would actually be pretty easy.

Yes, that is what I do. I put 2.5 gallons in the passive tank.

[kbsilver]

Originally Posted by montr

Yes, that is what I do. I put 2.5 gallons in the passive tank.

Sounds like a plan! It's been 12K miles since my last (dealer) DEF refill so shouldn't be long. I obtained the adapter hose from Mercedes (part# 000 583 22 04) which in theory should fit both the DEF fill port and the 2.5 gallon jug. So it 'should' be easy.

[mefferso]

Just an update to this. My "low DEF" warning finally showed up on my way to work tonight. I'm now at 21,000 miles on this take of DEF. Not too shabby i'd say! Gotta love it when diesel haters use 'having to add DEF' as some silly negative for cost ownership. This is less often than an oil change.

[kbsilver]

I've gone 14K miles on the last dealer DEF fill and still going. Longest ever since I had the car. Maybe the last DDE update changed the DEF consumption rate?

[montr]

Originally Posted by kbsilver

I've gone 14K miles on the last dealer DEF fill and still going. Longest ever since I had the car. Maybe the last DDE update changed the DEF consumption rate?

I am in the same boat. After the latest DDE reprogramming, it look like the DEF consumption and the regeneration frequency is reduced.