Injector Cleaning, Differential/Transmission Service

jerry_njDecember 22, 2009

I just got my 2004 Subaru Forester back from the dealer where I purchased a set of P215/60R16 (T speed rating) Pirelli P4 All Season tires, subject of another thread on this forum that helped me decide to buy new tires. The reason I purchased from the dealer was the price, yes lowest price. I got the set out the door for $419.19 including even the 7% NJ sales tax.

I figured, correctly, that the dealer is selling tires at low profit to get the cars in for an inspection which will "yield" lots of other work that should be done. Well, that's fine with me, I'm happy to hear what an experienced mechanic thinks the car needs. Among the accepted news was it needs new front disc brake pads... I may do that myself. To the point of the post subject (I did read some helpful threads on injector cleaners) the dealer shop also noted I had not had the car in for 30,000 mile service, notable of which is included (and not done by me already):

Fuel Induction Service, Transmission service, and differential (front and rear) service, and Throttle Plate Service.

The injectors is just a cleaning and I've had good luck getting 150,000+ miles out of a set of injectors by just adding a bottle of injector cleaner a couple of times a year. I also buy Shell gas often which is advertised to have really good injector cleaner (who knows?).

I have never changed fluids or oils in an automatic transmission or in differentials - is that a mistake? The service offered by the dealer includes a "Flush" which is stated to clean filters and screens. I think the differentials just get drained and refilled.

I also note a Throttle Plate Service, which I also wonder about - clean and service the plate and idle control valve to remove deposits... Never done that on past cars either.

I will check my owner manual again, but I don't think it calls for the above work in its recommended/required maintenance service.

I know people who do all the dealer service procedures, adding at least another $1,000 per 100,000 miles in preventive maintenance cost. These same people sometimes get 200,000+ miles out of their cars, there may be a relationship here.

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Brake pads-Yes.

Fuel Induction Service-No.

Transmission service-Yes per owners manual.

Differentials-Generally No, but there could be exceptions. I'm going under the assumption that the diffs take 80w 90. If they have ATF in them I'd change it.

Throttle Plate Service-No.


    Bookmark   December 22, 2009 at 11:39PM
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Every car needs attention, but rarely do two otherwise identical cars need the exact same services. Yet when at the dealer, quick lubes, and especially many of the chain stores you will see this "flush this and flush that" mentality.

Business consultants have pushed for the last decade or so that as a business "You can't make money fixing cars", you need to sell services. Their programs allow for one or two top technicians inside the organization who actually can fix cars. Then a few techs who are on the road to becoming a journeymen technicians, and then essentially entry level people which are of course on the low end of the pay scale. If the shop gives an entry level person even average difficulty work, the chance of a mistake occurring where the car has to come back is quite high. So they have in effect created an entire list of services that can be sold and performed where little to no experience is required by the tech and therefore they have a very low chance of a mistake occurring. These flush services are more profitable per hour than the shop can charge for major repairs. Consider this the second part of Newtons law, " where for every action there is an equal and opposite reaction". All of the price shopping for major repairs has stripped the profitability out of them, and at a dealer warranty work really tears the GP out of the equation. As a business they need a constant revenue stream to keep their doors open because true to the consultants description, they don't make money actually fixing broken cars so these services are sold and performed by an entry level group in order to subsidize the business when doing the more difficult, and especially warranty type repairs.

Now do you need the differentials flushed, and the transmission serviced, injectors cleaned, etc?

The fluid services are something I could only tell by looking at your owners manual, and by checking the conditions of the fluids myself. The problem here is even then the best that I can do is still subject to being a "subjective opinion".

The injectors would only REQUIRE cleaning if your car was presenting a drive-ability symptom, otherwise, a bottle of cleaner once a year is just fine. A road test with the scan tool would show me if there was any chance of this being needed.

The differentials are a simple drain and refill BTW, complete with easy to access drain and fill plugs (dipstick in some cases).

Throttle body service? Easy to tell just by looking, as well as by watching the PCM control the idle speed with a scan tool. Many cars have a minimum idle speed, and the idle can be commanded with a scan tool to the lowest speed that the engine can reach. If the engine reaches the minimum idle speed without stalling, then the answer is "No", you don't require servicing. But consider this, the consultants have said its cheaper for the customer and the business to simply sell the service, than it is to employ and pay a technician who can and will perform the steps to test this and find out. You have seen price pressure from other posters here in this forum through the years that are the basis for the consultants advising the way they do. (Newtons Law again, that was the original action).

Dollars and cents. The technician replacing a crankshaft in an engine is making the business around $100/hr gross profit while he costs the business $25-35 including benefits to be doing the repair. The flush routines can produce well over $250/hr gross profit for the business with close to minimum wage employees doing them. The crankshaft repair has a high risk of failure, the flushes extremely low risk. From that perspective, the consultants are correct. Anyone wonder why its difficult to find a real good technician/mechanic?

    Bookmark   December 23, 2009 at 5:50AM
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Thanks, I did carefully check my owner manual service recommendations. There is a call only to Inspect the transmission and differential levels. I can and do check to see they are at the full marks. The manual does call from replacing the fluids/oils if the vehicle is subject to "severe" service. I think mine are not... cold but moderate temperatures in NJ, paved roads almost always, no trailer towing, some stop-and-go driving for going to the store for bread and milk, but that's about 5 miles each way, so the car does get warmed up. This is for the subject Subaru.

I have a Suzuki AWD also, and it requires a differential oil change early-on, I think at 15K miles. Looks easy enough to do, as John says, low skill work. That's my "bag".

    Bookmark   December 23, 2009 at 9:12AM
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