ATF in Coolant

[DP3]

Did a little light hauling today and when I got home, the fan was racing like I'd never heard before and a few minutes later, I went back outside and saw this. 2020 Ram 1500 Laramie, 72K miles.
There was no indication of anything wrong on any gauge. This vehicle was purchased used a month ago and there is no warranty that I am aware of. My friend who is a top notch mechanic believes that the seals on the transmission heater or the mechanism itself has failed, as this seems to be the only place where the 2 fluids could mix. All of the fluid came from the overflow and there are traces of red (ATF) on the underside of the radiator cap. If anyone has insight (or a service manual??), I'd appreciate the advice.

 

[Rick3478]

Hate to see it, but yeah sounds likely. This function used to be accomplished with steel tube soldered into brass radiator tank, and you never had trouble with it. But modern assembly methods combined with thinner and lighter materials have sometimes led to consequences.

 

[Bt10]

May be obvious, but flush both systems. The “strawberry milkshake of death” is a thing with Nissan. The trans doesn’t live long running with that water base, if it has crossed. Trans is 100psi, coolant is 20psi, so may be safe. Obviously a new radiator is needed, hope you have warranty.

 

[mikeru82]

May be obvious, but flush both systems. The “strawberry milkshake of death” is a thing with Nissan. The trans doesn’t live long running with that water base, if it has crossed. Trans is 100psi, coolant is 20psi, so may be safe. Obviously a new radiator is needed, hope you have warranty.

Yeah, no one wants Nissan's SMOD mod.

@DP3 hopefully your transmission wasn't damaged by that the way that the Pathfinders and Xterras were. SMOD usually resulted in a transmission replacement.