I agree with MCW! We prefer CRC spray lube; but WD-40 certainly will work great here.
Use the red plastic "pipe" that the sprays come with, to get right onto the top of the threads. Also, use an absorbent rag to "envelope" the target area you're spraying so it doesn't get all over things & you.
The key is to spray it on, then LET IT SIT to do its job--for a few hours or overnight! Voila`
When you DO get that hose off, please DON'T re-use it on your replacement washer. Get a new one at your local appliance parts or hardware store. Make sure that the new hose has new washers in the ends & dab the hose & fitting threads with naval jelly or at least Vaseline to prevent further rust & to facilitate smooth removal next time: which should be once every couple of years to replace the hose end washers (a cheap insurance policy against a flooded laundry room floor).
Use a product called "PB Blaster". It specifically dissolves rust. Available at your local auto parts store or Wally Mart.
Or use any aerosol penetrate available at any automotive or hardware store. Spray on and let the product sit while it does its job. If you use a wrench be careful you don't rupture the water line. Then you will have problems.
Try some WD-40 and spray the rusted area well. Then wrap an old rag around the water faucet and use a pipe wrench and see if you can loosen the old hose.
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