We frequently have customers ask us what product to use to lubricate their Mail Boss locks. Well the answer is Tri-Flow, not WD-40!
The military developed WD-40 in the 1950s to be used as a water displacing substance in order to keep mechanical parts from rusting. It is a petroleum based product. As time went on, people discovered that it is also good for loosening parts that are stuck, and as a general household lubricant.
Then came Tri-Flow, which is a lighter petroleum based lubricant with microscopic particles of teflon in it. There is a huge debate over the uses of each product and which one is a better lubricant.
I have been using both for decades for different purposes. I find that WD-40 works best for loosening rusted or seized parts on cars and other equipment. But after I use it, I am sure to get it all off, because dirt has a tendency to stick to it.
Whereas for door hinges, locks and other outdoor uses, I think Tri-Flow is far superior. I find that Tri-Flow stays around longer and keeps these things working better for longer. I also have found that Tri-Flow does not attract dirt and debris as much as WD-40.
Being a designer and producer of Mail Boss high security mailboxes, I deal with people regularly that have lock issues. Most people don’t know they need to lubricate their locks frequently on these mailboxes, even though we suggest it on the paperwork that comes in the box. We get calls on locks that are rough to use or seized, and 95% of the time they go and get some Tri-Flow and the problem is solved. In northern climates when snow plows throw snow, water, sand and salt at the locks, we suggest flushing the lock out with Tri-Flow and it works.
I know the debate will continue strongly, but I strongly suggest using Tri-Flow in locks because I have seen proven results over many years.