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Transmission flush and Fuel Injection Service

I have a 2007 Matrix manual transmission with 30,000 miles and it’s been completely trouble-free. (I’m knocking on wood as I write this.) It was recommended that a Transmission Flush and Fuel Injection Service be done at 35K. Are these necessary services?

What does your owners manual say?


Just for laughs, ask them if they really can flush a manual transmission.


First I would question whoever made the recommendation. If it was your local quick oil change place, or chain outfit, the recommendation can be called a wallet flush.

Unless you are having some sort of problem there should be no reason for a fuel injection service.  Even if you are having a problem, don't start with a flush or some sort of general service,  Find out what the problem is and work from there. 

Since you have a manual transmission, You don't need it serviced until more like 75,000 miles and then you don't get a flush it is just a fluid change.  Even that could be considered overkill.

The place that you are using for maintenance on your car is very suspect, if they have made these recommendations. As was said, a manual tranmission CANNOT be “flushed”, and should not even need a change of its gear oil at 30k.

As to “fuel injector service”, unless you have mentioned specific driveability problems to the service people, this is something that is both superfluous and unnecessarily expensive.

Please tell us where you have been servicing your car. For your sake, I REALLY hope that it has not been Jiffy Lube!

Buy a bottle of fuel injector cleaner and pour it into your gas tank every other time you fill up and that should keep your injectors going. The cost is about $1.50 depending on brand name. Fuel injection service at a shop is about $100, so make sure you need it.

Money does the most when it circulates. Don’t you want the economy to improve by adding your money to the circulation? To answer your question, Yes, they are crooks.

Thanks to you all for confirming my thoughts on these recommendations that, to my dismay, came from the service station that been servicing my cars for the past 8 years. So now do you have any good and honest mechanics to recommend in the greater Hartford, CT area, ideally east of the river?

Most of the time an auto manufacturer advertises in the owner’s manuel and at the dealerships under the pretense that a service is needed. You probably don’t need these services, but the dealership likes the business. If that wasn’t true the dealership parts and service prices would be competitive. I said it once, and I’ll say it until the day I die, “The dealership is only there to make money and they would take advantage of their own mothers.” Unfortuneatley, most popular chain repair shops are nearly as dishonest.
Don’t get me wrong, regular service on your car’s engine will keep it running more efficiently. So yes, the trnsmission service would be a good idea…but the injection service? I have 225,000 miles on an Explorer and I have never had an injectors serviced…never. Now-a-days, the gas you put in your car keeps the injection system clean. I would just replace the gas filter.

Check out’s mechanic files.

Daniel; I’m reading from the 2007 Toyota maintanance and operation manual (the world’s most un-read best seller), and for your Matrix (similar to a Corolla) we have the following at 30,000 miles:

  1. Change cabin air filter
  2. Oil and filter change
  3. At 40,000 miles INSPECT fuel lines & connections, and and gas cap.
  4. If operating in very dusty or other adverse climate or off road conditions, change (not FLUSH) the manual gear box & differential fluids every 20,000 miles. This does not apply for normal driving.
  5. Other normal checks and replacements are manual transmission fluid and transfer case fluid. at 40,000 miles for AWD and 4wd only, no required service for 2 wheel drive Matrix!
  6. NO FUEL INJECTION SERVICE is specified; today’s gasolines do not require this, since there is enough detergent in them already. You can pout your own $9 bottle of flush in the gas tank if you so desire.

So your “trusted mechanic” really has NO CLUE as to what your Matrix really requires, and sells whatever service he has a machine for. In this case, fuel injection and automatic transmission flush!

Please read your owner’s amnual, copy out the relevant pages and show these to the service guy.

You will likely get a similar pitch from the Toyota dealer, but they would not want to flush a manual transmission.

I think this ‘flushing disease’ is the rule, rather than the exception, with most car mechanics, both dealers and independents (worst are the chains, of course). I was disappointed when the ‘expert mechanic’ on the Motor Week TV show came out with recommendations, both for flushing various systems AND using nitrogen in the tires! Sheesh!

I got the Fuel Injection Flush recommendation ($150) this morning at the Toyota dealership when I took my 2005 Scion XB in for its 30,000 service. So did the guy in front of me at the cashier line. They must be pushing that this month. I had never heard of it, didn’t get it, and came here to see what’s up. My car has no problems. The service guy said it was preventative. Time to find a new service provider! Thanks for the comments below, very helpful!

You did good. Unless you have specific problems, the fuel system flush is never worth it. Find a good independent mechanic (use the Car Talk ‘mechanic finder’). I quit using my dealer 10 years ago.

Sad to say it’s the MINI Cooper dealer in Scottsdale, AZ that’s recommending a “Manual Transmission Service” for $169 at 37,000 miles. Of course, it’s not in the owner’s manual and when asked, my Volvo service adviser just laughed.