That sounds about right, depending on how/if the cooling system has been maintained. By that time it probably be should be replaced due to loss of performance anyway.

I look at it as a maintaince part. If its 10 years old or older and I take the car on trips I will replace it. I rather not have it blow apart on a Sunday night 400 miles from home.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The key to your question is that you said "with proper service." With the system being flushed with cool, clear water and then replenished with fresh 50/50 antifreeze mixture every two years, barring crash or physical damage, the radiator will last forever unless you are VERY unlucky.

The internals of the radiator can possibly last forever, but, I find that these radiators suffer dramatically from an accumulation of debris from the exterior which drastically cuts airflow. The required removal and thorough cleaning of the fins with condenser cleaner is rarely performed due to the effort involved and the radiator is condemned as clogged..........which it is.........but, it's all external problems that are not easily visible.

So, the term "with proper service" needs to be extended to additionally service the tiny airflow passages through the fins.

When I drove 123's all the time, I had good luck keeping the fins clear by simply pressure washing from the back and front after getting as much pressure washing between condensor and radiator as possible, which isn't much. My cars were manuals, so it was very easy to pull the radiator at flush time and blow it and hose it and the condensor out at that time.

My $0.02,

This has been a fabulous thread and it seems everyone chipped in.

And I believe the consensus could be radiators with proper service
internally (flushing and replace fluid) and externally (clean the fins)
will last a very long time - 15 to 20 years. And that replacing them is not too
expensive and can be considered reasonable after a decade or two.

So.... expecting the worst from my 24 year old 300SD that is running warm
in the current 100+ degree heat out here. I order a new radiator.
It arrives next day in time for Labor Day weekend. Did not expect it
that fast, was pleasantly surprised (only $11 shipping).

Pull the old radiator and cannot see through the fins.
Decide to try (as suggested here by many) to externally clean and
start with water pressure from hose nozzle and then air pressure
then vacuum and repeat about three times.

Working from the back trying to blow the debris out the front (where it came in).

I am convinced I do not need the new radiator and that this will work, it was so clogged I could not believe it.

What I don't completely understand is how the Radiator gets all clogged but
the AC condenser does not.
I realize the radiator fins are much smaller, could this be it ??
And... what is the hair like substance all over the front ?
Is this a fungus growth ? It is very stringy and very difficult to remove.

So today I am at work and will get the real test going home tonight.
It will be over 100 again and I climb over a mountain, let's see if
I can blast the AC and keep it at 100c on the temp gauge.

I use this car on a 154 mile daily round trip commute. I like to keep it
in shape.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250