First off I'd like to say "hello"! It sure is nice to find a dedicated forum for older Allis-Chalmers equipment. I can tell there's a wealth of knowledge around here, and I'm sure I'm going to need to make good use of it!

I'm up on an 80-acre homestead in northern British Columbia and I just picked up this old girl the other day: an HD4 crawler loader with an Industrial-600 backhoe. All appears to be in good working order with no apparent leaks or anything.

I'm extremely new to owning/operating a piece of machinery like this though. The only other piece of equipment I've ever run in my life is my old gasoline-powered Massey-Ferguson 135 Deluxe tractor.

That being said, I want to make sure I give this old girl the best possible start to her new life. I have a lot of work I need her to do so I want to treat her just right!

I'm thinking of doing a complete fluid/filter change for everything. Is this a good idea? I assumed it would be but then I saw a post somewhere that suggested something might happen to seals if they were exposed to a 100% fluid change from what they've been sitting in for years... is there any truth to that?

Also I need to figure out what fluids to use for everything and any help would be much appreciated.

From preliminary online research, I'm led to understand that the torque converter/power shuttle clutch lubricant calling for "Type A" in the manual can be replaced by any Dextron or Dextron II ATF fluid. Is this correct?

I also saw on a post on a YesterdaysTractors forum that the "20-20W" in the manual for the transmission is supposedly an "engine-spec" designation and is equivalent to a "75W-80W gear oil spec". But that leaves me unsure still as to what I should be buying to put in there. Since it's for the transmission, wouldn't a regular modern ATF fluid be sufficient?

For the crankcase oil, the manual states "DS Series 3". I understand that the "DS" is supposed to stand for "Diesel Severe" but since I've never run or used a diesel machine before, I'm just wondering if this designation still exists today, or if there's a modern equivalent of disel-severe oil to buy?

The manual states "80 E.P." for the "final drives". I have no idea what kind of fluid this is....

And finally, the track rollers and idler all call for SAE 90. I assume that's still commonly available?

Thank for any and all help!

See recommendations and follow up to your questions below:

1. Buy a factory operators manual so as to aide you in servicing the machine.  I would opt to purchase both the AC HD4 loader operators manual and the AC HD4 dozer operators manual. The basis for this is that the loader operators manual does not cover lubrication and service instruction for the final drives but the dozer operation manual does.  John has a good recommendation above on the Service manual - that would be helfpul to have in support of service details on most aspects of the machine. 

2. The HD4 with backhoe was originally equipped with a 25 gallon permit hydraulic pump.  Be careful and feather your swing movements to the left and right while using the hoe. Feathering means to slowly move the hydraulic control with steady precise movement.  The control handle of the backhoe swing, dipper and bucket has a range of travel. Opening the handle to its full range of travel fast will result in moving the hoe quickly.  As you begin  - go slowly and experiment with the machines response to your operation.  Bearings on the final drives should be inspected for any leakage.  If there is leakage there then time to consider a reseal on the final drives.  Bearings and Seals are still available through reputable bearing supply vendors. 

3.Hydraulic system takes 10W-30 motor oil above 0 degress farenheit.  5w-20 below 0 degress farenheit.  A 15 gallon per minute pump was supplied for the HD4 dozer.  With a backhoe attached to a crawler there is greater volumetric hydraulic demand thus the larger displacement of 25 gpm to supply that demand.  Having spoken with AC Industrial Engineers while they were still with us (sadly no longer) they advised that the swing movement with a 25 gpm pump could be rather fast, thus causing  a stress moment at the end of its swing movement.  This tends to cause a wear and tear condition on the final drives which bare the weight or (dead load) of the machine when the moment is transferred.  This would also include a torsional load along the torque tube when the hoe is extend and or rotated to it full distance either to the right hand side or left hand side of the machine.  The stabilizer will take up some of that load but not all of it.   

4. Find the grease points on the loader and backhoe and use a generous amount of grease before putting it to use.  Sort through the grease fittings that won't accept grease and either boil them in hot water to mobilize the old grease or consider purchase of new fittings to replace the ones that won't accept grease. 

5. Engine Oil - 15w-40 Diesel engine oil  - I like Shell Rotella. 

6. Check and replace all filters and fluids. Again refer to the operators manual. 

7. Check the breather element on top of the hydraulic tank and make sure that it is working.  Remove any crud or debris from the screen with compressed air or could clean up with dish detergent and hot water just make sure that it is clean and dry before replacing on the hydraulic tank. 

8. There should be pipe plugs located in the housing of the final drive housing.  Remove those and insure that the compartment is full of 80.E.P oil. 

9. Transmission takes 12 1/4 quarts of 20-20W oil.  That reference is from the orginal manual. I doubt that 20-20w is readily available - check with your local oil vendor and secure an equivalent. 

10. Torque Converter and Power Shuttle Clutch - use Dexron Automatic Transmission Fluid ID # (B-10100) or modern equivalent. 

11. Track Rollers - NLGI#0 Calcium Soap Base Grease - Stateside I think some are using John Deere Cornhead grease due to its flowability in work application. 

12. To reiterate -  remove and Inspect Filters and Replace.  BTW - the filter in the hydraulic tank was or is obsolete and have not yet sourced and equivalent.  If you do wind up changing it and find a suitable replacement would you mind providing a reference to your replacement filter?  You may have better luck finding it in BP

13. A while back I did a filter listing for the H-4/HD4 and 650 series crawlers if you can find that on a search of this site that will provide a number of the filter references for both the HD-4 and 650 series crawler- loader, dozer with backhoe attachment. 

14. Last, if you need further help or support please reach out. I'll send you a PM with my contact information should you wish to reach out. 

Good Luck with this machine you will enjoy it! 

Orangeman