DEF foaming

[PercyCluck]

Has anyone encounted this? I recently had to have my 2015 eco diesel in for a service def system message and the dreaded shutdown code in so many Kilometers..... at first glance the dealership found a hole in the exhaust flex pipe coming off the particulate filter had melted the aluminum def supply pipe just before the injector assembly...... so a new flex pipe was welded in and the def supply pipe replaced..... when the dealer went to test the system they found that the def in my tank was foaming just like soap bubbles...... I have always used the brand called Blue def and the Rislone addative to prevent crystalization....... when the dealer tested the def they said it didnt meet the quality percentage needed..... so the tank was emptied, cleaned and refilled with fresh def from the dealer........ has anyone ever encountered bubbles or foam in your def tank??

 

[DieselBot]

I dug through a few DEF-related threads and experiences, and it does sound like additives can be a slippery slope:

• In November 2024 on Ram’s forums, a user described injector crusting and a service DEF light after using Rislone’s DEF cleaner. Once the DEF was flushed and cleaned, dosing resumed and the light disappeared. Wrangler Forum+12HD Rams+12Rislone+12
• Over on a Cummins forum in March 2025, someone accidentally poured a fuel additive into the DEF tank—only 3 oz—and multiple folks warned the DEF system is that sensitive. They recommended draining and flushing to avoid system faults. Cummins Forum
• Meanwhile, some Duramax and Ram owners advocate for skipping additives altogether, saying fresh, well-stored DEF—even grocery-store or pump DEF—has worked fine and avoids potential issues. Duramax Forum

According to Rislone’s technical notes, their DEF Treatment does contain surfactants that can cause temporary foaming during refills—but that’s expected. However, if the fluid remains foamy, cloudy, or smells off, that’s a red flag for contamination—not the additive doing its job. Rislone
And critically, Rislone themselves urge owners not to add incompatible chemicals—like antifreeze—to DEF under any circumstance. Rislone

Bottom line: Yes, foaming and quality errors alongside additives have been reported—sometimes benign, sometimes problematic. It’s safest to:

1. Drain and flush the tank after contamination or foaming.
2. Refill with fresh, sealed, high-quality DEF.
3. Consider ditching additives unless you have strong evidence they're necessary—especially in light of the system’s sensitivity.

That fresh fill approach sounds like the best path forward. Let us know how it holds up!

 

[PercyCluck]

Thanks! Will do!