I own a hammer drill (DeWalt d25263). I was using it today, and everything went well. But as I removed the SDS chisel bit that I was using, I saw a good bit of grease on the shank of the bit. I've never seen this before.

I'm worried that the tool has been compromised. The instructions say to take the drill to a repair shop to have it cleaned and lubricated after use. I would like to know how to clean and lubricate it myself.

I looked for videos on YouTube but didn't find anything that was helpful. Can you please tell me how to clean and lubricate a hammer drill?

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    Based on the model number your drill is not a hammer drill, but a rotary hammer drill. I own a rotary hammer drill of a different brand and it has an access hole where grease can be added. Since the DeWalt instructions don't mention adding grease yourself, my guess is that you probably have to remove part of the drill casing itself to access the lubrication ports, and I doubt that they want you to do that yourself, and depending on your skill level, it's probably not a good idea to do that. Just lubing around the chuck will not be enough and you at some point you will need to get lube added.
    – Itsme2003
    Commented Jan 17, 2020 at 6:48
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    The title should probably be changed to rotary hammer to reflect the content of the question and the answers.
    – mongo
    Commented Nov 30, 2020 at 15:14

2 Answers 2


Here's the relevant bit, which includes some liability tone:

Your tool was properly lubricated before leaving the factory. In from two to six months, depending upon use, take or send your tool to an authorized service center for a complete cleaning, inspection and lubrication. Tools used constantly on production jobs will need relubrication more often. Also, tools “out of service” for long periods should be relubricated before being put back to work.

The simple fact is that it doesn't need periodic lubrication for the casual user. It would be different if you were a professional drilling dozens of holes every day.

If you like, dab a little common grease in the chuck on occasion. There's a lot of slop (movement) in that type of chuck, and friction can heat things up if it's totally dry.

  • Cool, ok, will do. When you say "grease in the chuck," do you mean without unscrewing or taking something apart? Or could I just put grease on a bit and then insert it, to achieve the same goal?
    – Mark
    Commented Jan 16, 2020 at 20:29
  • The chuck is what holds the bit. I'm not referring to the chuck mount or anything internal. You could grease the bit as well. Really it's not that important. I've used hammerdrills in construction settings for many years without every lubricating the chuck. There's usually enough dust in there to do the job for me.
    – isherwood
    Commented Jan 16, 2020 at 20:31
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    The larger tools jack hammers and rotary hammers recommend that you put high performance grease on the bits before being inserted. Though I don't follow that advice very often. Commented Jan 17, 2020 at 0:19
  • @isherwood Do you have any guesses as to why grease leaked out while I was using it? I've used it lots of times, but this is the first time that happened. I had used it for about an hour chiseling up tiles today, and that's when I noticed it (as I was putting it away). Thanks!
    – Mark
    Commented Jan 17, 2020 at 0:32
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    The manual is one of the more hilarious self-serving bits of copy I've seen in a long time. One of my rotary hammer drills is >20 years old and while not out every day, it has earned its keep. It has never occurred to me to bring it to a service center for maintenance. What I use on the bit/chuck interface is this special grease: makitatools.com/products/details/194683-7 Commented Mar 26, 2023 at 21:27

I have both a Bosch rotary hammer and a DeWalt rotary hammer drill. The Bosch instructions say to apply grease from time to time on the bits. Bosch even includes a small tube of grease.

DeWalt instructions never mention adding grease to the bit. When the DeWalt was factory new, a bit inserted came out with a light coating of grease.

So I asked at the (now former) local DeWalt service center. The tech there told me that I should continue to put a light coating of grease on the bits, particularly during times of heavy use or after times of relative non-use.

She also said that more than one Bosch rotary hammer user has failed to grease, and they notice that the chuck is a little dry when servicing the chuck.

The sense I had after the conversation was that one could not grease the Bosch, or grease the DeWalt, and unless extensive use was made of the unit, or extensive grease was applied, it wouldn't make a big difference.

All bits get warm during use, particularly hammer use. If there is an abundance of grease in the chuck, some may get warmed up and migrate out. Even without an abundance of grease, some may weep out.

I decided to grease my DeWalt (absent instructions from the manufacturer) and continue to grease the Bosch. I use a synthetic high quality chassis grease.

  • Ok cool. You wrote I decided to grease my DeWalt Do you mean you just are adding grease to the bit?
    – Mark
    Commented Nov 30, 2020 at 1:29
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    Yes, use a light coating of grease on bit insertions, where I intend to operate the device for a period of time. If just for a single short operation, then no. Along with greasing comes the added job of cleaning out the concrete abrasive and grease paste that forms. But I am a intermittent user, so that is every couple of years.
    – mongo
    Commented Nov 30, 2020 at 13:06
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    I have a Bosch rotary hammer which has had periods of prolonged use and otherwise gets used for a few holes every couple of months. I've had it almost 20 years, and have added grease to the bits precisely once. I can't say it's suffered as a result.
    – SiHa
    Commented Nov 30, 2020 at 19:49

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