- As Long as I rinse the previous contents (milk) out, can I safely use this glass container for diluting antifreeze and putting it into my vehicle?
Not sure if you are talking a bout antifreeze for the radiator system or windshield deicers, but both systems are rugged enough that the do not require very pure water to be used. A washed milk container would suffice. The antifreeze wont disrupt the bottle and the bottle wont adulter the antifreeze
- Once I'm done can this go back into the recycle bin, or will trace amounts of antifreeze spoil it for recycling?
This somewhat depends on how it will be recycled. If you are putting it in general glass recycling then the bottle will become cullet that will heated to temperatures high enough to burn off any residue and it wont matter.
If you are returning the milk bottle to the producer for reuse then they have to clean them well enough to remove milk reside which is harder to remove than either your antifreeze or the bitterants in antifreeze. Any reputable bottler would expect some amount of non-milk substances in the bottles and clean them sufficiently well to make sure every bottle is clean and safe. Though I would recommended that you do rinse it before furnishing it to them out of courtesy.