'90 420 SEL Coolant low..
 

The coolant light on my 1990 420 SEL has been coming on every so often early in the morning for about 5 minutes, then it goes off. I'm assuming my coolant level is low. Can I just top the resivour off or do I have to flush it?

You can just add some if you want. The coolant is supposed to be replaced every 3 years though.
Gilly

tkamiya if you could post how to do that i would be very thankful.

I recommend putting water in too! Equal amts of coolant AND water.

!

I never thought about a bad sensor. Possible I suppose, but since it happens on cold start-up only, then goes out, this sounds like a classic slightly low coolant problem. As the car warms up, the coolant expands into the tank and then the level is fine.

Gilly