How to Flush and Replace the Oil in a Worm-Drive Circular Saw

As one of the more popular power tools on the market today, a worm-drive circular saw can be found on nearly every jobsite and in nearly every garage on the block. They are built for durability and high-performance and make any number of construction and demolition projects that much faster and simpler to complete.

Despite their popularity, only a handful of circ saw users fully appreciate the importance of regular maintenance and particularly of keeping their worm-drive circular saws properly oiled. In fact, its common for the lubricant in these tools to become thick, dirty and sludgy which can extremely damage the performance of the saw and can contribute to premature wear and ultimately the premature failure of the tool.
With just a little lube and a little extra time from those of us who glean so much work and happiness from our worm-drive circ saws, though, the early demise of these tools is entirely preventable.

Before explaining how to flush these bad-boys, though, I’ll start with a quick tip:
users should check the oil level in their worm-drive circular saws before each and every use. This takes only a moment and ensures your saw will perform at its best each and every time you use it. Note: the oil level in the tool should never fall below the lowest threads in the oil housing.

So, to continue, if you are one of those users who doesn’t keep the best tabs on your oil levels and now you have a sludgy mess on your hands and inside your saw, flushing and replacing the oil in your tool is the only way to revitalize its performance and longevity. Fortunately, though, although a bit more time consuming than simply topping-off the oil, flushing it and replacing it is a quite simple procedure.

Disclaimer: Although it is not necessary to remove the saw blade to flush the oil from a worm-drive circular sawl, it is always safer to remove it. This eliminates any chance of injury to both you and the saw blade. Also, when not running to the tool to warm old oil or flush with kerosene (*see below), ensure the tool is fully disengaged from its power source while working on it.

To begin, simply let the circular saw run for about one minute
. This allows the sludgy oil to warm and loosen making it simpler to drain. Next, remove the oil plug
. The oil plug is the metal nut that sits just above the oil reservoir (the reservoir should be clearly indicated with images or text). To remove the plug, use the wrench that came with the tool (the same one you use to remove the saw blade), and twist the plug off. Tip the saw upside-down allowing as much oil as possible to drain from the reservoir. 

After draining the sludgy oil, refill the oil reservoir with kerosene. Replace the oil plug and allow the tool to run for another minute. This pushes the kerosene throughout and entirely flushes the gear housing clearing it, and the reservoir, of any residual oil build-up. Invert the tool once more to drain
the kerosene entirely from the reservoir. 

Next, and last, you simply need to refill the reservoir with a brand specific lubricant. For example, if you use a Skil saw, you need to refill the reservoir with Skil oil. It is important that you use only these specific lubricants as other oils are not designed with the same particularities. 

Rest the tool on its foot atop a vertical surface (like a work bench or table) and fill the oil reservoir until oil spills slightly from the lowest point on the oil hole
(the part closest to the oil reservoir) and replace the oil plug.

Remember to check the oil in your worm-drive circular saw before each use, top-it off when it needs it, flush the oil when it gets nasty, and and you and that circ saw should be well on your way for a long life of successful productivity.