Could someone show or tell me the trick to getting the lids off these? I seem to remember that there is a key or something. Can I make some kind of tool?

Do you need to clean it ? Or just want the lid off? There is a snap ring under the cap. I have never tried to remove the tops because people have broken the bottle by doing so.

Hence the term FIL-PRUF!

Really just clean one.

Take a 5 gallon bucket and fill it with water that is Luke warm. Add some soap and submerge the bottle till it fills with water. Then take the bottle out and shake it and reapeat till clean. Then dump the bucket and put straight water in it. Repeat the process and let it dry out. This process works great. If you have hard water it may leave some stains. Good luck.

frankpl on here has Removed one or a few by drilling a few small holes around the cap, then w/ the HELP of a couple of Friends push the inside ring towards the glass & remove spout.

2nd page of Patent Drawing [below] shows the Oil Dispenser spout for filling the Fil-Pruf bottles.
http://www.google.com/patents?id=415oAAA...TEM&f=false

To clean;
I turn upside down & insert tube from WD-40 thru the flappers, then turn back over & squirt WD-40.
OR
Just pour paint thinner in top, let sit for awhile to loosen sludge in bottom, shake vigorously, pour out. Then use soap & water to remove the WD-40/paint thinner.

I have drilled 3 small holes equal distance apart where the ring grove is and like Dick said it takes a couple of extra hands but just use nails or small punches and push in all at the same time and it will push the snap ring in, lift and wiggle the spout and it should come off, I also use oven cleaner mixed with a little warm water and slosh it around in the bottle, that will knock the gunk loose ...Frank

Here is what is inside the Spout;

An excellent example of a well-engineered product!! Bottles were designed to be tamper-proof and prevent low quality oil from being substituted and sold as higher quality Mobiloil. 75-80 years later and we still can't get the lids off without a bunch of work..........

Richard

I used a product called F 239 cleaner to get all the oil sediment out of the bottom. It worked great - bottle clear with no hard water stains. I use this product to clean my boats and trucks in our business.

Who manufactures that stuff? What is it?