coolant level

Fill it up cold to just cover the sight glass. It doesn't make much sense for a company to want you to add coolant to hot engine and risk burning their customers . Most of the time after a few years, the sight glass become useless anyway. If you look down the filler neck, it extends into the reservoir. The proper level is about 1" below the the tube. If you fill it up to the tube or more, it'll push some out when it heats up.

 

If the sight glass gets dirty it can be removed and cleaned, they are available at any truck dealer. I use an 8 point socket to remove and replace them. Use gear oil on the threads and 'O" ring, very gently.

 

I never even thought to try, but I will now. Not worth it to drain coolant out just to change it, but if it has to be drained for another reason, it'd be a good time to clean or replace. Thanks,

 

When the engine is cold you screw one out and the new one in, you loose maybe a couple of Ounces at most. 99% 0f the cooling systems that have dirty sight glasses use DCA4. A coating not a cooling system protectant.