i have a basic harbor freight demo hammer that uses SDS MAX bits. its not clear how to keep it greased. there is a plasict cover on top (see pic) that has a huge chamber beneath. its not clear how much or what type of grease you are supposed to put in there.

also, is the idea that this grease is supposed to heat up and flow down the shaft there the bit attaches to keep it lubricated . i.e. that you do NOT have to also grease the bit itself?

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  • if it's leaking grease it may be defective. check the instructions.
    – Jasen
    Sep 27, 2023 at 2:39
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    The owner's manual should have maintenance instructions. There may also be a repair manual. Both can probably be downloaded from the manufacturer's website.
    – keshlam
    Sep 27, 2023 at 6:26

1 Answer 1


Having the same hammer and the same question: the manual doesn't say anything. Reddit says to use a decent all-purpose or moly grease.

Since I use my hammer very rarely since "the one big project" (breaking up the pad and a couple of steps that had been part of a garden shed on a hill) I decided to use the same wheel bearing grease I use on my trailer since I have a big tub of it.

I used up the tub the other day and decided to look up whether there is an easily found product (there is, Home Depot sells "Makita Hammer Grease" and there are a few others). They're all special order for me, so my seldom-used SDS hammer is still sharing axle grease with my trailer.

  • 1
    Welcome to Home Improvement. I'm not sure how this actually answers the question. Please read up on how to write a good answer then edit this to specifically answer the question. Thanks!
    – FreeMan
    Dec 5, 2023 at 16:42
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    This seems like a fine answer to me. It reference the manual and what products are available. Nothing wrong with leaving the choice to the owner.
    – isherwood
    Dec 5, 2023 at 17:01
  • yes, im guessing the exact type of grease is not critical. anything that is high temp / axel grease is probably ok. im still wondering though about how much you are supposed to put in that reservior... its huge and could hold a lot of grease if you filled it. also, im guessing the grease is suppose to leak out a bit and slde down the shaft of the bit to lubricate it on an ongoing basis Dec 7, 2023 at 11:59

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