czego82

I have 2011 ML, bought it used with 30k and I'm guessing it was serviced because now at 45k I still haven't added add blue. I thought the light supposed to come one when its low (10k per tank?) but nothing yet. Any thoughts?

marc hanna

Fill it up just in case. I think these have some issues if the run dry.

amg_w211

I would add some in there. The Adblue tank in the rear cargo bay holds about 7.5 gallons. Each 2.5 gallons of Adblue added will allow you to run about 5-6k miles. I get my Adblue from Home Depot for ~$12 per 2.5 gallon case (marketed as BlueDEF and made by Peak, who also makes antifreeze). Comes with a spout in the box for easy pour. It's compositionally the same (32.5% ultra pure automotive grade urea and the rest is distilled water) as the way overpriced Adblue from the dealer.

http://m.homedepot.com/p/BlueDEF-2-5-gal-Diesel-Exhaust-Fluid-DEF002/204804290?keyword=BlueDEF&searchtype=text

czego82

Thank you, so full tank should last 15 to 18k miles. Do you know when the light should come on?

amg_w211

Your warning light for low DEF should come on at anytime based on your driven mileage. The amount of DEF used depends on the type of driving you do (freeway vs city vs ambient temperatures, etc). I personally would not wait for the warning message to come on as you'll eventually need to add it (and sooner than later in your case). As a guesstimate, I would add in a minimum of 5 gallons DEF now and then add in 5 gallons every 10-12k of driving. If you overfill DEF, it will just spill to the rear underbody, which you can just hose off.

czego82

sounds good. I wanted to burn as much of whatever was in there as lifespan on it is 2 years and I wasn't sure how long its been there and but based that its already at 15k miles, there should be very little left.