M923A1 Oil Change Intervals

[Enty45]

I have a 1985 M923A1, and it is recommended to change the oil every 3,000 miles or 3 months, whichever hits first. Is this something to strictly adhere to or can you put more miles on before changing? I don't drive the truck often, but I do want stay on top with maintenance.

Thanks a lot

 

[jaws4518]

I have a 1985 M923A1, and it is recommended to change the oil every 3,000 miles or 3 months, whichever hits first. Is this something to strictly adhere to or can you put more miles on before changing? I don't drive the truck often, but I do want stay on top with maintenance.

Thanks a lot

I go by the running hours usually. 250 oil change, 500 trans oil. I just flushed my differentials @500 hrs. The oil was pretty dirty. Oil gets expensive to change every 3 months. I'll just say I haven't had any problems with those intervals. I changed my transfer case @500 too.

 

[ericp351]

Oil analysis preferred, but not always workable! I go by 3,000 miles- long time for me- and use modern oil with lots of detergents and Total Base # to kill acids, and I do stretch "time". Cost-benefit for me is look for a good price/sale and write off oil and filter cost as part of the game to protect engine. Oil dilution is a factor that ain't figured in for modern cars/ syn. oil thinking when they advertise 10,000 mile 'super oils'. Probably this is a "10 men = 10 heartfelt and smart opinions" type of question. 15w-40 or 5O, Rotella T-4 or completion at 3K VERY hard to argue down!

 

[jaws4518]

Oil analysis preferred, but not always workable! I go by 3,000 miles- long time for me- and use modern oil with lots of detergents and Total Base # to kill acids, and I do stretch "time". Cost-benefit for me is look for a good price/sale and write off oil and filter cost as part of the game to protect engine. Oil dilution is a factor that ain't figured in for modern cars/ syn. oil thinking when they advertise 10,000 mile 'super oils'. Probably this is a "10 men = 10 heartfelt and smart opinions" type of question. 15w-40 or 5O, Rotella T-4 or completion at 3K VERY hard to argue down!

Do you think 250 hrs is too long for a NHC 250? I was reading somewhere that anything with a turbo will do better shedding heat with frequent oil changes which I would concur with the 3k miles. I'm certainly no expert so I just listen and learn. 3000 / 55 = 54.545 hours. Let's say the average travel speed is 25 mph. 3000 / 25 = 120 hrs. That sounds more like it. Maybe every 150 hours? I apologize for bring topics like this back into the spot light but it doesn't hurt to bring this routine maintenance stuff up so that inquiring minds can see the latest posts on old topics.

 

[simp5782]

I ran small cams and big cams at 10,000mile intervals without bypass filters. 2 or 3000miles a week.

If you want you can spend your money on a puradyn bypass filter kit and never worry about changing the oil again

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@Suprman had some of the systems with a diffuser plate at one point

 

[ericp351]

You asked, so I'll give you my opinion. I think 250 hrs ESPECIALLY if lots of starts/ stops, is a bit long. If clean , tight engine and great oil, lots of steady load, long hot running, IE industrial type operation, 250 hrs may be OK. Oil analysis is probably the way to figure that out. Also, be realistic as to your av. speed. Some of these trucks can be used at 45MPH as "Texas pick-ups", others at 5 MPH on a farm or logging. Most between that. Good luck, your call. 250 hrs ain't 1000. May be OK, I'd not push it.

 

[jaws4518]

You asked, so I'll give you my opinion. I think 250 hrs ESPECIALLY if lots of starts/ stops, is a bit long. If clean , tight engine and great oil, lots of steady load, long hot running, IE industrial type operation, 250 hrs may be OK. Oil analysis is probably the way to figure that out. Also, be realistic as to your av. speed. Some of these trucks can be used at 45MPH as "Texas pick-ups", others at 5 MPH on a farm or logging. Most between that. Good luck, your call. 250 hrs ain't 1000. May be OK, I'd not push it.

Probably more like 100. Still that might be a little long too. I'm coming up on 100 hrs soon. I will probably do an oil analysis after the next 100.

 

[jaws4518]

Every time I do a full service oil change I start questioning the different oil types. I heard 15w/40 engine oil is good for everything in 800/900 series trucks. Is this true. I would like to use one oil type from this point forward. Any suggestions?

 

[juanprado]

15w40 dinosaur oil
3000 miles or once a year to remove water/condensation
That is what I do. Ymmv

 

[jaws4518]

15w40 dinosaur oil
3000 miles or once a year to remove water/condensation
That is what I do. Ymmv

I'm not sure what you mean by "dinosaur" oil? My question is... is 15w/40 good for everything including transmission? I heard that it is... Is there any reason not to use it for power steering, transmission, hydraulics? I'm tired of juggling oil types for older equipment. I'm not speaking of differentials, transfer case, or final drives. Mainly hydraulics and transmissions.

 

[juanprado]

I am not a fan of mixing Synthetic oil in an engine that has mostly seen plain petroleum based oil. 15w40 is usually sufficient in most climates. Straight 30w or 40w if hot and never sees cold weather. Most HD fleet oil is typically 15w40. My rig Does not see much service and I converted to a spin on filter so real easy to do an oil change.

I like to use power steering oil as it has anti foam additives and others specifically for power steering that dexron transmission fluid does not. They are both 10w just different additives and color but using dexron is fine also. Check your power stg dipstick and see what color it is?

Transmission oil type has millions of posts here and opinions. Are you carrying weight and loads on a regular basis or running empty? Oe it tended to be filled with Motor oil but some units would flush and fill with dexron. My m923 came already converted to dexron and I do not carry loads and been happy with it. It shifts smoothly and no issues. Allison now also has some newer fluids they recommend. Some think motor oil is better if loaded regularly. I would see what color the fluid is and stay with that unless you are going to change both filters and flush/refill.

 

[jaws4518]

I am not a fan of mixing Synthetic oil in an engine that has mostly seen plain petroleum based oil. 15w40 is usually sufficient in most climates. Straight 30w or 40w if hot and never sees cold weather. Most HD fleet oil is typically 15w40. My rig Does not see much service and I converted to a spin on filter so real easy to do an oil change.

I like to use power steering oil as it has anti foam additives and others specifically for power steering that dexron transmission fluid does not. They are both 10w just different additives and color but using dexron is fine also. Check your power stg dipstick and see what color it is?

Transmission oil type has millions of posts here and opinions. Are you carrying weight and loads on a regular basis or running empty? Oe it tended to be filled with Motor oil but some units would flush and fill with dexron. My m923 came already converted to dexron and I do not carry loads and been happy with it. It shifts smoothly and no issues. Allison now also has some newer fluids they recommend. Some think motor oil is better if loaded regularly. I would see what color the fluid is and stay with that unless you are going to change both filters and flush/refill.

This is a working M929A1. I haul and pull a a 10K trailer. I have AW32 in the transmission right now and it has been fine. I just want to get away from hydraulic oils if I can use 15w/40 in all hydraulic power systems. If I use motor oil I don't have to worry about mixing hydraulic oils. I have had two issues where hydraulic oil did not blend well. I don't know if this is true but I read that water is part of the molecular process as an additive. Do you know if that is true? Dexron is a transmission fluid, right?

 

[ericp351]

My 2 cents. Oil questions are "big can O worms" issues. Dextron is common trans fluid. GM hydromantic for decades. Very common and widely used. Many hyd systems can use motor oil. Expect noise cold/ sluggish. Hyd oil is cheaper, usually thinner, and lacks additives hyd systems do not need. My concern with your system is your tranny. It will function with hyd oil, but you are scrimping on additives. Think plow horse with only hay-no grain. This comes up lots with vintage Ford/ Massey Ferg Tractors. Much better, similar, and available choice probably "Universal Tractor Fluid". Go to your local tractor supply type store and read label for the tractors I listed. Basically Hyd oil + additives for trans and rear axle. I think of it as a bridge between basic hyd oil and the Detron's with even more "modern" additives. Easy to buy in 2 1/2 and bigger pails. Good luck. Post script- jump around viscosities lots- get lots of leaks...

 

[jaws4518]

My 2 cents. Oil questions are "big can O worms" issues. Dextron is common trans fluid. GM hydromantic for decades. Very common and widely used. Many hyd systems can use motor oil. Expect noise cold/ sluggish. Hyd oil is cheaper, usually thinner, and lacks additives hyd systems do not need. My concern with your system is your tranny. It will function with hyd oil, but you are scrimping on additives. Think plow horse with only hay-no grain. This comes up lots with vintage Ford/ Massey Ferg Tractors. Much better, similar, and available choice probably "Universal Tractor Fluid". Go to your local tractor supply type store and read label for the tractors I listed. Basically Hyd oil + additives for trans and rear axle. I think of it as a bridge between basic hyd oil and the Detron's with even more "modern" additives. Easy to buy in 2 1/2 and bigger pails. Good luck. Post script- jump around viscosities lots- get lots of leaks...

Thank you for your 2 cents. Yes, oils and varying opinions are as cloudy as my 10 gals of fresh lift cylinder oil. I'm not off track on what I have been doing, I just want to feel confident that I'm using the right oils for my application and geographic area. Haven't had any real problems other than a mixing problem AW32 and AW46 on my 1978 D5b and M929A1 dump lift. I just didn't get a good flush.

You said,"My concern with your system is your tranny. It will function with hyd oil, but you are scrimping on additives." So, the TM says HD30 for M929 transmission. Same goes with my CAT D5b power-shift transmission. Non-detergent oils are expensive. They are old school now! I believe the 1982 CAT D7G TM says 15/40 in everything. Why not? The VFD guys around here are using 15w/40 in M900 series trucks to simplify and save money. They don't run their trucks that often though. I've used Traveler AW46 in my power steering and hydraulic components without problems. I'm really not worried about anything other than the transmissions. Mainly the dozer transmissions!

 

[ericp351]

You probably have a very good handle on your gear. I also see no trouble in mixing 10-20W hyd oil with 20-30 wt. My A2 Allison trans has the Gov Spec engine oil in. I still think Universal Trans Fluid may be better than your Hyd oil. Just a bit more money than your hyd oils. your fight!