Come to think of it, how come y'all have half a quart of engine oil and three pumps of axle grease in your sealed cooling systems, anyway?

I feel like what happened is that there was information talking about different scenarios where you would want to flush the cooling system and they all got mashed together into "do this every time". For instance:

SHOUT for coolent flush? MB recommended!

If you have oil in your cooling system it's for a reason and there's a procedure for that (Mercedes makes an alkaline cleaner or, apparently, they also use laundry detergent, but only if there's a known issue like a head gasket failure). But suddenly everyone seemed to get obsessed with the idea that their cooling system is greasy and you have to pump soap through it every time you do a flush. It makes no sense when you think about it.

Also interesting that MB doesn't recommend flushes unless there's an actual problem. Yet we're all out here doing flushes like it's an oil change (was guilty of this myself years ago). Been an interesting rabbit hole to go down for sure.

You're welcome, good luck with the flush!

Ya gotta lube that water pump somehow!

It's not oil, it's gassed out crap from the 30 year old rubber hoses .

Once this is done that should be it but few take the time to do it properly .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I've flushed the cooling system on an MB exactly one time. I don't expect to ever need to do it again. I put only distilled water a antifreeze in it.

__________________
84 300SD
85 380SE
83 528e
95 318ic

I also use only distilled water and antifreeze. Every time I change the antifreeze i completely drain the block using both the radiator drain valve AND drain the engine block so the system is EMPTY. I have flushed it multiple times using the citric flush followed by shout laundry using the prestone back flush kit and STILL the rust continues....

What kind of coolant is everyone using? G-05 still the go-to?

I got the Pentosin Pentofrost as it meets MB spec and it's what FCP Euro had at a better price.

I still use the G-05 in my 240D and my Cherokees. Though from what I understand the Green Stuff is now very similar to the G-05.

seems like you need to individually flush each component after letting the acid sit for a while.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Are you thinking flush the radiator separately from flushing the engine block?

..Maybe just suffer driving with the heater on ~ the heater core sits below the entry point of the coolant and is always a sediment trap by design .

That was the hardest thing to get clean in my badly neglected W12's .

I'd think the job was done and a few weeks later the coolant had that devilish red crud in the coolant yet again .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Agreed Nate, the heater core is a big sediment trap.
When I rehabilitated the cooling system on 'Stormcloud', I did it in two stages.

First stage omitted the heater core bypassing it completely.
I was concerned the heater core might spring a leak.
The radiator itself was shot and needed to be re-cored.
‘Stormcloud’ – Cooling system remediation – Part 1

Second stage was just rehabilitating the heater core.
It was leak-free when tested before and also leak-free when tested after remediation.
‘Stormcloud’ - Coolling System Remediation–Part 2

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

When I did my 240, I removed the heater core and cleaned out. I should have had it sonic cleaned or such by a radiator shop. I might have done the Citric flush with it in. My radiator went bad a few month after.
Now why I did flushes on the 240D and 2000 XJ is that the previous owner(s) didn't know of the word maintenance. The 240D's hoses looked like they were the ones from a Chilton or Hayes manual. Yes, that bad.
On the XJ, I had changed the coolant a year before. I was changing the radiator to a 3 row that was new. The coolant came out brown. I tried to filter the coolant out. No luck. I did several flushes, as I wrote before. I'd add a few flushed with 50% vinegar. When I was done, it still burped some crud into the reservoir tank. I poured that out, and am going to run it a while.