Wild difference in maintenance schedules?

[mark pruett]

I have an 05 Dodge Dakota, and I was looking through the maintenance schedules and noticed this rather strange difference:

On the "normal" schedule, there is no scheduled change of the differential lube.

On the "severe" schedule, it asks you to change it every 15,000 miles with 75w-140 synthetic.

This seems to be a little extreme; on one hand, you have a very high interval (none!), and on the other, it seems really frequent, and ultimately pretty costly.

Does this seem right? I qualify for the severe service one (who wouldn't?), but don't really relish changing my differential fluid every 15000 miles. Could I stretch it to say.. 45000?

 

[benjamming]

My '94 Grand Am has something similar. If it's severy duty (manual lists the conditions) change the ATF every 15k miles; otherwise every 100k miles.
My dad's '04 Tacoma doesn't specify an interval for the ATF unless used for towing, etc & then it's every 30k miles I believe.

How many times has it been changed thus far? How many miles on the pickup? What is it that qualifies you for severe service - towing?

 

[onion]

At the risk of offending those who say 'trust the engineers'...

I've noticed that even with vehicles of similar year models, with essentially the same engines and transmissions, maintanence intervals reccommended in the owners manuals can vary wildly depending on the year and brand-name. (Exactly how different can a '97 Olds Cutlass BE from a '97 Lumina?) Makes me think that suggested maintanence intervals are influenced more by marketing and bean-counting than by anything resembling scientific testing.

I'd suggest that if you tow or otherwise use the truck hard, stick with 15k. Otherwise, change it early the first time, then 45k thereafter would be more than adequate with a good synthetic.

 

[mstrjon32]

Out of curiosity, would you be able to outline some of the differences between the maintenance schedules for the '97 Cutlass and '97 Lumina?

I used to own a '97 Monte Carlo (a.k.a. 2-door Lumina) and recently I was flipping through the owner's manual of my friends '94 Cutlass Convertible, and noticed that other than the pretty color pictures for the Olds manual, the maintenance schedules, and in fact, most of the manual contents really were very similar.

 

[Steve S]

There are lots of poor engineers. That is why the engineers from India are doing well.

 

[TimVipond]

Quote:

---

I have an 05 Dodge Dakota, and I was looking through the maintenance schedules and noticed this rather strange difference:

On the "normal" schedule, there is no scheduled change of the differential lube.

On the "severe" schedule, it asks you to change it every 15,000 miles with 75w-140 synthetic.

This seems to be a little extreme; on one hand, you have a very high interval (none!), and on the other, it seems really frequent, and ultimately pretty costly.

Does this seem right? I qualify for the severe service one (who wouldn't?), but don't really relish changing my differential fluid every 15000 miles. Could I stretch it to say.. 45000?

---

Amsoil warrants for parts and labor their 75W140 Severe Gear lube for your application for 50,000 severe miles.

 

[sprintman]

Think about the variations between diferent countries for the same vehicle?

 

[onion]

I've no doubt that India has its share of poor engineers. Theirs work for peanuts, though... THAT's why they're doing 'well'.

The '97 Lumina manual in question is about 200 miles west of here... and the '97 Olds Cutlass Supreme manual is about 800 miles east of here... so I can't give you direct quotes. What I recall is that they both have a 3100 engine and a 4T60E transmission, yet the service intervals listed for the transmissions were very different. If I remember right, the Lumina listed 30k/100k service intervals for the transmission (severe service/normal service), whereas the Olds listed 50K severe and lifetime fill for normal service. There were also significant differences in other areas like air filters, etc. Makes me doubt just how precisely these maintanence intervals have been tested.

 

[bulwnkl]

I would suggest that this serves to partially illustrate how close to the "ragged edge" vehicles are these days in terms of engineering them to do their job and NOTHING more. The job of most pickups these days is to transport a single occupant to and from work, and to the store now and then, all whilst conveying an extra 2-3,000 pounds of its own dead weight just to make a marketing claim in a brochure or on TV. Nevertheless, to achieve the maximum fuel economy while dragging all that flab around for nothing, the transmissions and axles are made such that, if you actually do use the rated capabilities, you have to run very expensive synthetic fluids throughout and change them every couple days because they're burned up or used up protecting the undersized parts from the overweight chassis.

...Or not, but that's what it looks like to me.

 

[Shannow]

Quote:

---

I've noticed that even with vehicles of similar year models, with essentially the same engines and transmissions, maintanence intervals reccommended in the owners manuals can vary wildly depending on the year and brand-name. (Exactly how different can a '97 Olds Cutlass BE from a '97 Lumina?) Makes me think that suggested maintanence intervals are influenced more by marketing and bean-counting than by anything resembling scientific testing.

---

Yep,
for utes down here, they used to be considered all severe service (5,000km service), espacially tradesman's vehicles. The OEMs then ran them to 10,000.

Mitsubishi were the first to run to 15,000, and featured it in their advertising campaigns as a significant feature of their models, meaing less downtime for tradesmen.

 

[mark pruett]

In response to the question of how many miles I have on my Dakota: 21,500 as of this morning. I generally put about 60 miles per day on it, with about half of that being in stop and go traffic.

I don't tow anything, and I don't carry much that's particularly heavy. Basically the only things that put me on the severe service schedule are that 1) I drive in 90+ degree heat on a regular basis (all summer), drive in sub-32 degree temperature somewhat regularly (all winter), and do stop and go driving frequently. Other than that, I don't idle much, etc...


I was figuring I'd probably do it at about 30-40, and maybe get a UOA on it (they do UOAs on gear oil, don't they?) and see if that's a reasonable interval.

 

[1sttruck]

The fluid changes for the AAM axles in my 3/4 ton Dodge are the same, 15k or nothing. I did 15k two times, 30k the next, will stick with 15k thru warranty, and will then probably switch back to a 30k interval.

'Severe duty' can involve towing max loads in hot weather, so the engineers needed to address possible wear issues with a short change interval. That's a worst case situation, and the axles are robust enough to not need a fluid change under normal use. I'll guess that the engineers would prefer a table of change intevals vs load conditions, but marekting got involved so users ended up with two schedules, normal and severe duty. Just as well, considering typical owners.

 

[kotzy]

The bottom line is what is severe duty. If I were fording streams all day I would think we need have a look at the lubes. As far as towing or loading the axles heavy I don't know, EP lubes were designed to stand the pressures of hypoid gear sets, and unless your using far to light an axle for the work your doing, I really don't see any great
problem. A 12 inch Rockwell rear or a Dana 80 will pull 3 ton night after night for 90 100 thousand miles without a lubricant change. I have seen the Rockwell's go over 200. If the lube gets gritty or white and full of metal you need to do something.