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Direct Injection engine maintenance

I have a 2009 Cadillac CTS with a 3.6 direct injection engine with 33,000 miles. At my most recent oil change, the service tech recommended a fuel system clean up (approx $400!) as part of the 30,000 mile maintenance schedule. Is this because of the DI engine and the carbon buildup concerns? Is this REALLY necessary?


How does your car run? If it isn’t acting up (of course it’s not), then you don’t need the wallet, uh, fuel system cleaning.

Does it mention this service in the Owner’s manual or is it dealer recommended service? I’m betting dealer.

My trusted mechanic offers the Motovac service for about ~$120. I’ve had it done on a few of my vehicles, but these days I add a bottle of Chevron Techron or Seafoam to the gas tank once a year or so.

If the vehicle is running normally I would pass on the dealer service.


If I were in the automobile product business, I would take my cue from the pharmaceutical industry. The drug companies buy televison time and make commercials where a bunch of symptoms are listed and then one is supposed to ask his/her doctor if a particular medication would be right for that condition. There are gullible people that, after seeing the commercial, have those symptoms and want their doctors to prescribe that drug. Well, I would describe a lot of automotive symptoms and these gullible people would believe that their cars had these problems and ask their mechanics if this treatment would be right for their cars. These people would imagine that their cars had these problems. I would then give mechanics a kick-back to use this snake oil product.
As others have said, you don’t need a fuel system cleaning. Modern gasolines have detergents that normally do this job.

If I had a DI engine I would try to use Top Tier gas, more detergents. I would also put in a bottle of Techron once a year or so. I would not pay for a dealer EFI cleaning unless I had problems.

$400…Ask the service writer to define “fuel system clean-up” …What exactly are they going to do for $400? If he replies “clean the injectors”, you say “How? Will you remove them and clean them on a test bench?” At that point, I think the service writer will decide you probably didn’t need fuel system cleaning after all and move on to that spiffy 2013 calender that was included free with your oil change…

It is conceivable that your car will benefit from a fuel system cleanup. Direct injection engines are known to be more susceptible to carbon deposits than the previous generation of engines because of the way they operate. But $400? No way!

Handle this yourself by adding a bottle of Techron to the gas tank. Do this every six months or so.

Note: Your owner’s manual may recommend you use only Top Tier fuel in your car. Top Tier gasoline is rated to have enhanced detergent properties to reduce or eliminate carbon buildup. If you use only Top Tier gas you can even eliminate the routine Techron treatment. See:

The owners manual for the 2009 Cadillac CTS is at

It recommends the use of TOP TIER gasolines, and then says for customers who do not use it, they recommend adding one bottle of “GM Feel System Treatment PLUS” to the tank at every oil change.

Whether you agree or not with what the manual states, it’s a far cry from what the service tech recommends.

Don’t forget that most service techs are under financial pressure or orders from the management to recommend such services.

The “experts” I go to always recommend an additive when I change my Castrol Syntec. Gotta love those guys. The other experts just do the work I ask them to unless they have time to make more money. Their recommendations vary.

Thanks for your suggestions. You confirmed what I was kinda thinking. I very much appreciate your input.

My understanding is that some Direct Injection engines are developing a few problems with deposits on the stems of the intake valves and right underneath the valve head as the injector spray no longer hits that area. This could be especially true on engines that use a little bit of oil and can even be true on non-DI engines.
If a problem like this is suspected one can try running a cleaner through an intake manifold vacuum port but you could get this done anywhere for much less than 400 dollars.

With the engine fully warmed up, idling, and in gear note how it idles. Heavy deposits on intake stems often cause a disruption in airflow around the valve head and this may come across as a subtle engine miss, stumble, etc.
If it idles smooth then I wouldn’t even worry about it.