Dash01

My coolant has some oil in it, but no coolant in the oil, so I'm changing oil cooler O rings, etc.

What's the best way to flush out oil residue from the coolant system?

MAGK944

I used this stuff and it removes oil residue, it’s also cheap and available from Walmart. If you search there’s a bunch of videos on YouTube about how to use it. One extra thing I did before I flushed was remove all the rubber coolant hoses and cleaned the insides by pulling a shop towel through them until they were clean.

Paul Waterloo

Intermix is a common occurrence on the 996.1 cars when the head cracks. It is normally cleaned up by using Shout and hot water.

https://rennlist.com/forums/996-foru...-clean-up.html

Tom M'Guinn

I did this on a vintage Mercedes last year. Lots of the Mercedes guys use Shout! too, but unless you have a place where you can run and drain tons of water through the system, it's pretty hard to get rid of all the foam... Mercedes sells a Citrus cleaner that will clean out the system almost too well. It breaks down scale and sediment sooo well that it can reveal leaks that might otherwise stay plugged up for years. That might sound like a good thing....until the heater core leaks. For me, the Prestone stuff shown above is a happy medium. It's made to do this job, so reasonably easy to use and flush out, but without being quite as harsh as the Mercedes Citrus flush.

Dash01

Thanks, all, this helps. I'll proceed in an abundance of caution and first flush with Shout, rinse, then the Prestone stuff, then rinse, then finish with proper coolant and distilled water.

87944turbo

I don't have a specific recommendation, but this is something I came across a while back when I was having a sludge issue w/another vehicle. Lots of good information here.

http://www.sancarlosradiator.com/VoltageDrop/flush.htm

Noahs944

Whatever you use, I recommend not putting your good coolant in, until you run the engine up to temp (including bleeding) with the detergent-water for a few cycles. It will take a few attempts & you might never be able to clean your coolant tank as well as you'd hoped, but you'll be okay.