Is anyone up to speed with all the various models? I’m looking at a 3/8 Compact Fuel impact but I’m not sure if its worth spending the extra for the M18 over the M12. It’ll be for home mechanicing on my car.

Not an expert by any means but I’d be looking at m12 fuel stuff I reckon. I’ve used it volunteering at a woodworking place and it seems really nice to use and plenty powerful enough.

It’s kind of brushless+ I think.

We have a couple of the Milwaukee 1/2″ drive Fuel M18 units at work, on high setting they will strip or snap a 12mm bolt.

The only thing I would say is 3/8″ drive what you would use on a car for any heavy duty wrenching?

It will be fine I guess for whizzing up medium stuff that has no real torque setting than “tight” but things like say a crankshaft pulley will firstly be kin tight and secondly around the 32mm range where I’m not sure there are many sockets in 3/8″.

I’m more of a 1/2″ drive man on cars, probably why I have over 200 sockets in that size 😮

Some tests I’ve seen suggest that the 3/8 one produces way more torque than the 1/2 inch despite the published figures.
Use an adapter to 1/2 inch and it gets even better due to the increase in effective weight of the anvil.

1/2 inch will more than meet your needs. Lots of commercial garages are now using Milwaukee tools and tend to go for the 1/2 inch unless they are working on heavy equipment.

1/2 is all you need for car stuff. Heavy equipment needs much heaver duty stuff.

Eurocarparts are the UK distributor and frequently have heavily discounted deals on Milwaukee particularly M18 1/2″ you shouldn’t have to pay full price if you are patient and wait for the next Special Offer which should be along any time 😉

Rockhopper

Some tests I’ve seen suggest that the 3/8 one produces way more torque than the 1/2 inch despite the published figures.
Use an adapter to 1/2 inch and it gets even better due to the increase in effective weight of the anvil.

Not sure what use that would be given the torque figures they produce anyway and a 3/8″ output square shaft will wear out quicker as its smaller. I don’t like using adapters on socket stuff.

I think a few might have thought you were looking at 3/4″ drive?

you shouldn’t have to pay full price if you are patient and wait for the next Special Offer which should be along any time

That’s right.
If the 2pm special offer mega discount sale doesn’t have it, the 3pm one will

“Use an adapter to 1/2 inch”

You’ll lose a lot of impact power between the driver & adapter as the slack has to be taken up before torque can transfer.

Use an adapter to 1/2 inch and it gets even better due to the increase in effective weight of the anvil.

Adding weight to the anvil won’t increase torque, and as above, the adapter will probably reduce it.

I’d agree with the suggestion of going for 1/2″. For home mechanicing, I’m more interested in being able to undo really tight stuff easily than being able to do easy stuff quickly.

Was sceptical when my mate passed me his well used/battered (he’s a proper mechanic) cordless Milwaukee 1/2 inch impact driver (think it’s one of the biggest ones they do) to spin off 36mm drivshaft nuts torqued to 120nm, span them off no bother!

Heavy brute of a thing with a right hoof of a battery hanging off it!

I have a m12 fuel 3/8 ‘sub – compact’ and for the size it is really nice: esp with a smaller battery which makes it fit into the most awkward of places: in behind calipers, subframe bolts up beside exhaust hangers etc.

Model number is M12FIW38

I wouldnt be without it now: but that small size has its downside – its not as powerful as bigger guns which all 18v ones are. Pretty obvious really!

Also – I think the most important thing with any decent impact wrench is how much control you have. It is SO EASY to snap bolts, studs, strip nuts. You will know this already but for stubborn fasteners you need to be able to turn them down from 100% and learn to alternate tighten, loosen, heat, plusgas, tighen, loosen… The M12 is great for control.

If I had to start again from zero batteries & chargers I would actually get another Makita DTW300Z (an 18v compact)rather than another m12 : its longer than the M12, but thinner. Even though the 1/2 means longer sockets too. The Makita manages more real world stuff including stubborn wheel bolts etc.

So to actually answer your question: you probably want both 🙂