Was doing a check on the wife's car today (2000 Outback, EJ25 SOHC 333,000 miles) and found the timing belt is showing some cracking, so I'll be doing that job next week when parts get here. I had to remove the coolant overflow tank to get to the timing cover and found an inch and half of this at the bottom of it.
Never seen that sort of stuff before. Pulled the radiator cap and found a little more sludge. It's like a fluffy sponge cake consistency. Not oily. Radiator took maybe a quart of fluid to top it off. It has been performing normally and running at normal temperature. Any thoughts on this? Car seems perfectly fine. Just due for a new timing belt and found this weird stuff.
Since I'll be draining the radiator anyway, I'm planning on a good flush at the very least.