Soft goey stuff under radiator cap?

[The motor guy]

What is this soft mashed potato like stuff just around the radiator fill neck? I've used nothing but zerex g05 coolant in this truck from day one. The inside fins of the radiator look nice and clean. Brand new looking.

 

[JohnnyG]

Looks like some additives have "condensed" in that low flow area. I wouldn't worry about it. Clean it if you wish.

 

[The motor guy]

Looks like some additives have "condensed" in that low flow area. I wouldn't worry about it. Clean it if you wish.

Probably would help if it was filled up all the way. I had a hose leak and the level was where you see it in the pick. About a 1/3 of the way down

 

[Chris142]

Silicate drop out.

 

[The motor guy]

Silicate drop out.

Time to change it then? I went ahead and drained it out. It's been about 5 years