How do I adjust an Air Way liquid filled automobile compass?

On the bottom of mine there are 2 screws. 1 for north south, the other for east west. You simply calibrate it using a modern very accurate digital compass. Make sure you perform the calibration on a non metallic surface such as a glass table with a srewless wooden frame or other suitable flat non magnetic surface. If it is installed were it will be permenently mounted would be the best scenario, like from your windshield in your car. This way the calibration would counter any straying from true magnetic north due to the metal frame in your car. True magnetic north is what the compass reads so it is ever changing. Some people don't know that. You can use the calibration screws to adjust it to mapped north and south also depending on your personal preference. Either way it will be good for rough navigation needs. If you know you need to be heading in a certain direction to get home on a map and you are heading in the wrong direction too long on the compass you know you made a wrong turn. The compass in my car saved me countless gallons of fuel by letting me know I was travelling in the wrong direction so I could quickly make changes in direction. It's most useful when you are away from home and you don't now the roads. Hope this helps you.
George K. NEPA

This may help, luckily Automotive doesn't need to be as accurate as many roads are a 90 degrees, a compass would have to be way off.
I was coming back from the Everglades in the middle of the night and a sttele for sharpening knoves threw my compass off 100 degrees, needless to say I spent 3 days/nights gathering rain water, catch fish for food. That when I got a nice Hand Bearing Compass to help reduce the error caused by deviation by a magnetic field.
I would observe compass going up and then back down a road(North and west would be nice), then a east and west road.
https://www1.nga.mil/ProductsService...ents/HoMCA.pdf


Found this on an old post:

* ADJUSTING THE COMPASS
DO NOT USE STEEL SCREWDRIVER (THIS WILL AFFECT THE COMPASS MAGNETS) USE A DIME TO TURN REGULATOR SCREWS
* 1. Head North. Turn the regulator marked NS, very slowly, until the dial reads either N or S.
* 2. Head East. Turn the regulator marked EW, slowly, until the dial reads E.
* 3. Head South. If the compass does not read exactly on "S" -- Then turn the NS regulator just enough to remove only one-half of error.
* 4. Head West. Turn EW regulator just enough to remove only one-half of the error. Follow the same procedure as in step 3.

It's weird you asked how to adjust an Air Way Oil filled compass in particular. I just sold mine on Ebay. It was from 1966 the year I was born. It was new in the box, but the box was worn so I tossed it. It was never even installed. If you would like to see a nice picture of a NIB condition Air way here is the link:
Antique Air Way Automobile Compass : eBay Motors (item 150408140230 end time Jan-28-10 20:17:44 PST)
If the link goes down and it will in 60 days or less you can Email me for some nice Hi Res shots of something pretty rare. You own a nice Compass. Hold on to it. I got mine for free at a church sale, 1$ a bag sale anyway, and sold it for $28 bucks with the shipping. Anyway, a road twists and turns to avoid natural barriers unless you are crossing the great plains I wouldn't recommend using a road to calibrate it. Unless you don't mind it being off +/- 90 degrees. LOL
George

What I said was, if you go north, south, east and west, and the compass confirms this, leave it alone, a couple of degrees is less important in automotive.

The adjustment screws on an Air Way oil filed compass only adjust 3 degrees + or - in either direction for the N/S or E/W adjustment screws on the bottom of the compass. They are very acurrate even if they are adjusted wrong. I'm sure the asker was not worried about having to drink his own urine and eating insects to survive or whatever because his mounted automobile compass was off... lol If you get that lost in a car... Whoa!

I said I gatehered rainwater, Urine may be in one of your storys,
So are you agreeing if you go north, south, east and west, and the compass is relatively close, you could leave it alone?