[GreekboyD]

I know the 335d can hold 5.3 gallons of it. I like doing oil changes twice a year which for me means every 5,000 miles or 8,000 kilometres. I've already picked up the oil and filter but I'm not sure how much of the urea I'd need.

Anyone?

[Sabersix]

I'd guess about two gallons.

[kbsilver]

I believe it best not to keep topping off the DEF, but rather wait for the 999 miles to no start illuminates, then fill it up. The DEF has a shelf life. By allowing it to go near empty before refilling, you consume most the old fluid instead of diluting new fluid with old if you keep topping off.

[GreekboyD]

Thanks guys. That's a good point kbsilver.

[TotalPower]

urea is used at 2-3% of what your fuel consumption is. has nothing to do with your oil.

[GreekboyD]

I'm aware of that. I was just trying to figure out how much I'd need after 5,000 miles / 8,000 kilometres.

[kbsilver]

Originally Posted by TotalPower

urea is used at 2-3% of what your fuel consumption is. has nothing to do with your oil.

Actually it's closer to 1.3% (.013). E90 holds 6 gals of DEF. Say that we use 5.5 gallons in 13K miles at an average of 29 MPG. 5.5 gallons divided by 448 gallons is .0122