How much of an issue is the puddle? Does it cause a hazard when walking to your car? Does it cause damage to your property (the stuff stored in the garage)? Do you 'need' perfection or is a DIY patch (and an obvious one) good enough for you?

When it comes to leveling concrete it can be easy (assuming you have been taught some tricks of the trade AND have worked with the SLC product before) or it can be frustrating (none of the above).

Technically you can rough up the concrete (give it a deep clean with detergents...then rinse, rinse, rinse and rinse again). You can prime it. Both of these are pretty easy. The tough part is the SLC. It is not self-leveling and it can be tricky to get the mixture right.

Remember: SLC have MAXIMUM thicknesses as well as MINIMUM thicknesses. You have to choose the correct SLC AND IT'S OWN PRIMER to do the job properly. You have to know the max/min of the product and you have to leave an edge that you grind down later.

As an aside, epoxy coating isn't going to do anything for the dip. Epoxy is a coating. It isn't a 'build up' product like SLC. To fix the dip, the epoxy professional STILL has to fix the dip with SLC.

I've used SLC successfully several times to level out a small section of floor, but there are challenges. Getting the right thickness and ensuring you get a good bond have already been mentioned. It is also relatively explensive compared to other concrete.

The other challenge is that when mixed properly it is truly self leveling. You cannot use a screed board or other means to get any type of slope or make it go in a different direction. SLC works fine if you have borders on all sides and/or the SLC is filling a shallow bowl area.

Pour some water in this area ahead of time and verify that it won't run off to one side. Garage floors are often sloped toward the roll-up door, or sometimes they have a very slight crown in the middle.

Bruce