If you are lubricating door hinges, commercial store-front glass door locks, and the actual deadbolt bolts and latches, keep on using the original formula. Why? Because the oil-based lubricant is going to have a longer life span.
However, now that WD-40 has introduced the silicon based spray, I have quit using the original formula as a lubricant for the pins in the locks themselves. If you do come across an ancient lock cylinder that is oily-gluey-sticky because of years of being oiled, flush it with the old WD-40. When you are finished, follow up with the silicon-based product. When you do, be sure to flush the lock cylinder well.
The new silicon-based product leaves behind a nice dry lubricant while creating a water-proof barrier and a residual dry coating.
As a locksmith, I have since quit using Houdini. My experience has been that Houdini does not last very long in lock applications. Not only that, when you spray Houdini, it shoots out like a geyser, soaks you, the door, and your customer's merchandise. Why Houdini cannot design a nice, easy-to-use spray can is beyond belief.
Be sure to add WD-40 silicone spray to your arsenal. You can find it Lowe's or Home Depot. Just look for the yellow, black, and green can.
