Paging Rick (or other Automotive Gurus)

Factual Questions
1

So I went to Jiffy Lube yesterday and was set upon by the cashier with the “manufacturers recommendations.”

IIRC, they included transfer case fluid replacement, front and rear differential, transmission flush, coolant flush and a host of other things that supposedly needed to be done. Now I have never had any of these done on any vehicles I’ve ever owned, nor do I know of any friend that has. So here are my questions…Ready?

  1. How important/necessary are these “recommendations”?

  2. Are there some that are a)absolutely necessary, b) should be done, or c) good idea? Which is which?

  3. Are any simply bad ideas, or otherwise worthless?

  4. Lastly and a harder question…are there any “studies” (if they exist I’m sure they’d be done by fleet managers) that identify the “optimum” maintenance level for a vehicle? IOW, what level of maintenance should I be doing if I wanted to run a vehicle for 250,000 miles?

Thanks

2

What kind of vehicle and how many miles? I’d at least say they’re all good ideas but I’m always leery of having someone like Jiffy lube work on mine. The proper way to do differentials is by draining, opening the differential, cleaning/inspecting, and refilling. Jiffy Lube’s idea of differential service is to suck out the fluid and put some new in. Not worth $50 for me.

3

One is a Toyota 4Runner w/ 175,000 miles

The others are service vans w/ 100,000 to 150,000 miles.

I buy used service vehicles when they go to auction and use them for HVAC/Plumbing/Elec service. Typically they were owned by AT&T, Time Warner, Dayton Power & Light, Comcast, etc before I get them.

They have between 60,000 and 90,000 miles when I buy them. Some are 6 cyl, some 8 cyl.

4

IIRC, they included transfer case fluid replacement, front and rear differential, transmission flush, coolant flush…
These are all legitimate maintenance services that are recommended by vehicle manufacturers.

…and a host of other things…
This isn’t very helpful when asking for this type of advice. Some of those things may be legitimate, some may not (plenty of places recommend services that are not called for). If you want an accurate assessment, list the exact items suggested, and provide the year, make, model, and engine size (not how many cylinders - the specific size in liters or cubic inches) of the vehicle.

Now I have never had any of these done on any vehicles I’ve ever owned, nor do I know of any friend that has.
Sounds like you and your friends forgo normal scheduled maintenance. I’m not particulary surprised about not having a differential fluid service, but never a coolant flush? Never a (automatic) transmission service? Strikes me as mighty odd to have never done those.

1) How important/necessary are these “recommendations”?
Important enough that the vehicle manufacturer lists them on their official maintenance schedule. Have you never referred to those schedules?

2) Are there some that are a)absolutely necessary, b) should be done, or c) good idea?
Sure, some could be considered more important than others. Engine oil and automatic transmission fluid break down, and the consequences of their failure tend to be repair bills in the thousands of dollars. Engine coolant breaks down, and the consequences of the resultant corrosion can be in the hundreds of dollars. Differential oil seldom causes a problem, with many vehicles going well over 100,000 miles without trouble.

3) Are any simply bad ideas, or otherwise worthless?
As far as factory-recommended maintenance, generally not. If it’s dealer-recommened or shop-recommended, sometimes yes.

4) Lastly and a harder question…are there any “studies” (if they exist I’m sure they’d be done by fleet managers) that identify the “optimum” maintenance level for a vehicle? IOW, what level of maintenance should I be doing if I wanted to run a vehicle for 250,000 miles?
I’m sure there are, though I don’t have the info on them. What I do have is 35 years of field experience servicing and repairing vehicles, and I have observed plenty of expensive repairs that could have been avoided or significantly delayed if proper maintnenance had been done. I would say if you want that kind of longevity, follow the manufacturer’s recommendations and maybe a few addtitional things recommended by a competent, honorable shop.

It’s a virtual certainty that the service vehicles you have bought from working fleets had the recommended maintenance done.

5

Some differentials don’t have drain plugs, and the official procedure is to remove a cover to drain them. However, the majority have drain plugs and the factory recommended service is to simply drain and refill the fluid. I wouldn’t have any qualms about simply replacing the fluid regardless of which type it is.

6

There is what may well be an urban legend that if you don’t have the transmission fluid changed at a certain point (various figures are given, generally around 50+K miles or so), its better to not have it changed until the transmission dies. The reason given is that the new fluid dislodges all the old gunk which then proceeds to gum up the works inside the transmission and bring about premature expiration of it. Now, I’m inclined to think this is a case of someone realizing they’re way past their recommended service date for the transmission, getting it done, and then the transmission simply failing, as it would have done without having the fluid changed, but I don’t know. I’ll leave it to the experts like Gary T and Rick to answer. If it is true, then its something to think about, because the fleet vehicles probably didhave the fluid changed when they were supposed to, and if you’re not following the manufacturers instructions, you could be setting yourself up for real trouble.

7

Gary T is certainly the expert on manufacturer’s recommendations & practical retail vehicle user experience. I think it would be very interesting to learn what sort of maintenance schedule actual large fleet operators really use.

For example, what do rental car companies use? They aren’t looking for real longevity, since they get rid of the cars after a year & 50K miles or so but they are looking for reliability during that time.

Likewise, and more relevant to the OP, what does, say, AT&T cable, or a railroad or the USPS do with their vehicles?. They intend to run them for >100K miles (in some cases >300K miles) and don’t want breakdowns or expensive major repairs.

I expect the big fleets build their schedules from the manufacturer’s recommendations, but they could easily decide, for example, that conventional motor oil will last well enough that doubling the recommended 3000 mile interval saves more money than it costs.

Sadly, I don’t think we have any large fleet manager types around. Maybe Mr. Bus Guy could tell us about his maintenance department’s policies?

8

My sister worked as a fluids analyst for a large bus operation. They would routinely take fluid samples (oil, transmission, coolant) from the fleet vehicles and do spectrographic and other tests on them for wear products, additive breakdown, etc. They kept test result trend charts for each vehicle and would change the fluids when the tests indicated it was necessary. A simple rule like “every six months or 3,000 miles” isn’t the most cost effective method for large fleets.

9

What he said.
If I can add a few things
If not changed the antifreeze corrosion inhibitors break down. When this happens, electrolysis sets in and in an engine with a iron block, aluminum head, and a brass radiator, the aluminum gets eaten away from the head, and something (not sure just what) get deposited in the radiator. Eventually either the head gasket blows because the water passage has eroded to the point that the gasket can no longer seal, or the radiator gets plugged to the point that the engine overheats. In the first case, the head has to be replaced as there is nothing to seal against a new gasket. In the second, a new radiator is needed. This used to be a huge problem in the late 1970s early 1980 when Japanese cars did not come with recommendations for coolant changes.

I would also like to add that you should read your owner’s manual to get an idea of how often these services should be done. Iffy Lube was recently raked over the coals on local TV here for telling customers that their upsells were factory recommendations when in fact the TV guy had letters from the car makers that said such services were not necessary.