Alright so this may be a dumb question but we learn something new everyday right? on a cold engine my coolant reservoir tank sits empty. When it warms up it sits about half way between full and empty. Is it okay to just add more without a flush? If so should it be pure or does it need to be diluted with water. When should I add it and how much should I add. All awnsers are helpful. Thanks

 

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your reservoir should have fluid in it when its cold. so put fluid in it

 

there are lines demarcating what should be the acceptable COLD and HOT levels of fluid.

 

Yeah it's not normal to have an empty reservoir tank at any temp. Also, don't put straight coolant in there, put a 50/50 mix.

 

When the engine is cold the coolant level in reservoir should be in cold and when the engine is hot ( normal working temp) the Level should be in hot
You can add either distilled water or coolant 50% consent ration