My 300CE is a 1988 with 72,000 (verified) miles. The current situation is
When cold - or hot, it's difficult to start and get to hold idle. It
usually takes some accelerator to get it to stay running at this point. It
runs like a top at highway speeds with engine temps in the 90 range. After
some driving, it continues to run - even at idle. However, the idle oil
pressure is barely at the 1 mark, the idle is a bit rough, and temps start
to creep upwards when the car sits with the engine on.
An aside: After driving, if I shut the car off and turn it back on say in a
few minutes, the temp gauge indicates a very warm engine (110-115) but that
cools down shortly after starting. Not sure if there are some electric
cooling fans that are supposed to help with this as the car sits with the
engine off or not.