Transmission service the manual way
 

Anyone try flushing the transmission through the cooler lines. I was thinking of just unscrewing one of the transmission cooler lines, overfill the transmission with new fluid, start the car and wait until new fluid starts pouring out.

Good idea on an older 560SEL?

No, not a good idea. Drain the transmission and torque converter, replace the filter. Re-install pan, fill with 4.5qts.....start engine, let it idle a couple minutes, then add the remaining 2.5-3qts.

Actually, for the later model cars, flushing the transmission via the cooling lines is exactly what MB recommends in cases where it's deemed necessary. For routine maintenance though, I'd say it's overkill.

I think it's silly to use the cooler line method for cars with a torque converter drain plug. The cooler line method is more messy and you still get mixing of the fluids where new fluid is pushing out the old.

The cooler line method is only messy if you try to use the return line.

I did put a short piece of hose aimed up on the cooler fitting I removed too.

If you drain to clear 2L bottles its also very, very easy to see what is
coming out.

Real Men drop the pan clean it,change filter.

Anyone agree with this method ?

Yes. That is the correct method for changing the ATF.

That is the method published in the shop manual.