I always lock my hubs when there's snow on the ground, it says in the suzuki manual it's ok to leave them locked with the transfer case in 2wd. but dont' leave the transfercase in 4wd without the hubs locked or run in 4wd on dry asphault. SO. in short the only thing that it'll damage is gas milage and maybe alittle extra wear but nothing major. I would repack those hubs though if their frozen. it's a pretty simple procedure. I repacked mine with high quality axle grease. as long as the grease has a good temperature rating and it NOT long strand grease it should be fine.

-Mike

You say its a pretty simple procedure to repack with grease. Do you have a walk through? Im at my begining with 4x4 vehicles and not sure how to do this.

I threw out my auto hubs on my trail rig, and went to Warn Premium hubs.  They have this cool feature (optional) called a HUB FUSE.  The idea is, when you push it too hard, instead of breaking a CV joint, or a Ring Gear, or Pinion Gear, the hub fuse disintegrates.

The fuses cost about $20 for two of them, and you can replace them without removing the wheel, in about 15 minutes or less.

HOWEVER:  If you switch to Warn Premium Hubs, you WILL have a problem with hub bolts backing out (yes, even with Loctite on 'em).  SO - to overcome this, you ALSO install Spidertrax Super Hub Bolt Kit:  http://www.spidertrax.com/drivetrain_shb.htm

You say its a pretty simple procedure to repack with grease. Do you have a walk through? Im at my begining with 4x4 vehicles and not sure how to do this.

I recommend getting a service manual from Walmart or Canadian Tire. I have a Chiltons but Haynes is just as good. there are others too. very handy.

Well, I repacked mine in the garage (or in the driveway if that's all you got) with some allan keys, and socket set, some rags and a floorjack.I'll try to remember all the details, if I"m wrong someone here will point it out.

1) jack the suckerup , use some axle stands - much safer.
2) take wheel lugs off and remove the tire and the plastic ring that fits around the metal part of the hub, that just slides off.
3)remove the 6 allen bolts from the face of the hub, be careful of the gasket, you should probably replace it everytime you open it but I didn't cus mine was in good shape.
4) remove the six(or less?) bolts around the outside of the hub casing. This removes the hub from the truck itself.

IF you look around (especially at the Warn fused hubs) you can get an idea of how these things fit together. from the outside of the truck in heres how it goes on manual hubs.

outside cap - this has the allankey bolts in it.
free-lock switch- this is the rotating selector switch   visible from the outside that you use to change from free to lock.
spring - this sits beween the free-lock switch and the spring seat to hold the seat firm against the guide notches on the shaft of the freelock switch.
spring seat - little metal ring with prongs that sits on the clutch (fuse if it's a fused hub)
clutch(or fuse) - round cog looking piece that slides and acutally engages the hub casing(and subsequently the wheel that it's bolted to.) to the axle itself.

After you get a good idea of what's going on, you can take apart each piece laying them on a clean surface in order as not to forget how they go together! after cleaning each one indiviually and giving them a nice healthy coat of axle grease ( any will do, just check out the temperature ratings, and make sure it's not long strand grease as it will clog up the hub) you can start assembling. I wouldn't use WD-40 as it displaces any other types of grease then evaporates leaving the metal unprotected.

You can start to reasemble but be careful that you allign the groves in the hub casing, spring seat, clutch(orfuse). also note that the spring has to be compressed and placed between the lock-free switch and the spring seat ring that must be "hooked" into the lock-free switch's shaft. make sure that you do all of this in the FREE Position with the clutch pulled towards the outside of the vehicle.

The six bolts tighten to 25Nm or 159inch lbs and the allenkey bolts tighten to 12Nm or 106 inch lbs.

Finally test to make sure everything works smoothly when put back together before driving it down the road.

I hope this helps a little, pick up one of those manuals. I think they're like 12bucks or something.  Good luck, just go slow and think it over. it's not that complicated.

Thank you!