Barney#007

Hi all: I just purchased a 2012 S550 with 40,100 miles in sweet condition. I looked at all service records from MB and don't see where coolant was ever changed? I am afraid the heater core will become clogged if not changed so I want to schedule it to get flushed and filled with new coolant. Agree?
Thanks,

Michael Barnett

BOTUS

check user manual - does it still say 15 years....

cruiser02

I changed mine at 50,000 miles as part of a major service of all fluids including transmission service, differential fluid, brake fluid, coolant, coils and spark plugs. Coolant alone was about $200 at independent Mercedes only shop, so not too bat at all.

Consider going 70/30 or 60/40 water/coolant mix if you live in a hot/warm climate. I will do that next time.

BOTUS

at the factory they fill it correctly without air pockets, using water that is designed not to rot the engine or build up filth and using an antifreeze they know is compatible with ALL the engine parts gaskets and seals - and with a life expectancy of 15 years

the worst thing most owners can do is disturb this with nasty tap water and the wrong type of antifreeze and ruin the car - especially as most leave it half empty

cruiser02

Coolant should be done by professionals, I've never attempted it due to the air pockets and the mess that it can cause at a home garage. 15 years is a long time for any fluid that goes through heat cycles daily, even cars that only do shorter trips (low mileage) heat up the coolant quickly.

It makes me wonder how the manufacturer comes up with their guidelines and change intervals. Do they take into account that my car is in a hot climate (California) vs. the others that live in colder ones (Northern Europe/Canada)?

BOTUS

isn't that the point of the cooling system (and its fans and thermostat) - they should all run at the same temp... I agree 15 years is a lot - but we've been making cars for 100 years and understood this stuff by 2005 - they should know...

if high mileage the rad should rot out before 15 years

so below 100k no road salt on the rad - thermostat, heater valve and coolant change 12 to 16 years

>150k miles thermostat, heater valve, water pump, radiator, AC condenser, and coolant change (on anything over 10 years old)

cruiser02

They should all run at the same temp. However, the car that consistently operates in >100 f ambient temps will work harder to maintain operating temps vs. one that is in <60 f.

I was recently on vacation in South America, it was very hot and very humid. Their ACs were on max, all day, saw quite a few cars that overheated.

Jaap

Really?
I've done it on my S500 and it was pretty easy to be honest.
Drain at the bottom of the rad and fill at the top, that's about it.
After 10km driving i had to add another liter or so.

cruiser02

Hmm that doesn’t sound too bad at all. Honestly, I didn’t even research much since it was only $200 and I bundled it with the other services.

It’s a longer story but my other car has two cooling systems and about 10 radiators. When I upgraded the intercoolers I was told by everyone to be very careful or air bubbles, which can cause hot spots. So I took it to a shop instead.

Jaap

Oh yeah if you have the S600 with the turbos you get a second coolant circuit that is an absolute nightmare to bleed.