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2008 DTS
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Recently on a trip back home I got 34 mpg which was awesome, at one point with tail wind I averaged 36 mpg. with all my other cars the first thing I always did was rip out the air system and put a cold air tubing and build my own box and put a 9" K&N . I don't want to do that with my Caddy as I like how quiet it is. However, has anyone had experience with putting in a replacement air filter that was either Kool Blue or K&N? What were the gains on the mpgs. Did the volume of the car increase markedly?
 

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2018 GMC Sierra, 1995 Jeep Wrangler
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A K&N replacement air filter isn't worth the $$$ IMO. A CAI will make your car significantly louder and give you a negligible HP gain. I've never had any CAI (I've owned K&N, And Injen) cause my mpg to increase. I've had to clean the throttle bodies and mass air flow sensors of 2 out of the 3 vehicles I've put CAIs on because of the extra smut sucked into the intake. In the case of the K&N, re-oiling the cone filter with the recommended amount of oil caused my MAFS to gum up with oil and a service engine soon light to come on.

I like the additional intake noise on my pickup, but HATED it on my Escalade. I took the CAI off my Lade after 2 weeks.
 

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I use K&N filters in all my vehicles, and have been for the last 10+ years.. I average 2-3 mpg more on the hwy. No noticeable gain in HP. It pays for itself over time. Never had an issue with buildup on the MAF sensor or excessive dirt in the throttle body, which should be wiped clean every $15K.
 

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K&N is very good at marketing.......but if you read their "test reports" you'll see that they make no horsepower gain claims for a filter-only installation.

Your car already has a very efficient cold air intake which is sized larger than the engine can handle at WOT. Any radical changes to that system, and as Rolex stated, you increase intake noise, not power. Absent before and after dyno tests and extended road mileage averaging, the extra intake noise afforded by a so-called CAI is always subjectively perceived as "power"

If you're looking for a good filter with significantly more filter media area, look at a WIX replacement for your application. Same in the oil filter department.
 

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2008 DTS Lux III (assembled January 31, 2008)
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The only place that I've installed a K&N air filter is on the exhaust of my central vacuum. It sure does keep the dust down inside the basement, and I swear that the vacuum sucks even better with the filter charger.
 

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2005 Cadillac DeVille DTS
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Best application for a K&N air filter is placing it behind one of the rear tires, shifting in reverse, and listening to the noise it makes.

Speaking of noise... why not put one of the fart cans on the exhaust like stupid the kids do with those crappy four cylinder cars? I guess they think making the car sound like a weed whacker makes it go faster. I love seeing the looks on their faces from my rear-view mirror after they've been blown away by an old man in a Cadillac.

Joe
 

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Wow, tough crowd. But, I agree that a K&N is a waste of money and can lead to damage on the MAFS. I've bought about a half dozen K&N filters over the years with no power or MPG gains and GM replaced the MAFS on my CTS.
 

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Recently on a trip back home I got 34 mpg which was awesome, at one point with tail wind I averaged 36 mpg. with all my other cars the first thing I always did was rip out the air system and put a cold air tubing and build my own box and put a 9" K&N .

If you are getting 34 to 36 MPG...I wouldn't do "ANYTHING" to it except lock the hood so that no one can mess with it.
Thats great mileage and the K&N ain't gonna help it any.

Texas Jim
 

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2006 DTS Lux III
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Man how are you getting 35 mpg? Was your trip back home all downhill? What kind of DTS do you have, a Lux or Perf? I'm getting about 21 mpg in a mix of freeway and street driving on my daily commute and I can't imagine getting that much more on a pure interstate drive. 25 mpg yes. 35 mpg... ...are you in the Hybrid DTS? I've seen the hybrid Escalades.

Ciao,
Daniel
 

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2008 DTS LUX III - Gold Mist traded for 2004 Tbird
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Best I can due on the Interstate at 75 is about 24....maybe 24.3................
 

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The "BEST" I can get at about 75/80, "IF" I am real careful, is 23 in my 2006 Performance Sedan.

Usually get about 22. :hmm:
I "WISH" it would get 34/36 as previous poster stated that his does.

Texas Jim
 

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BTW....on the K&N.
An engine is an air pump. The more air you can put through it, the more gas you will put through it....the more power you will develop.
The computers will make sure the ratio remains the same even as you increase the amount of air.
This ratio BTW is called the stoichiometric ratio and is 14.7 to 1.

K&N allows more air to go through.
Usually doesn't make much difference since there are two constrictions, not just one.
The intake is restricted to how much air can go in....and the exhaust is restricted (for Audible Sound reasons) to how much air can come out.


Some cars, like the DTS for example have a very restrictive muffler.
The car is not built for performance. (The "performance model" is in comparison to the Lux and in no way is a true performance car. Sorry, but I have had performance cars)
Therefore the muffler's main job to keep these cars QUIET.
Could the K&N help? Very Unlikely. No matter how much you open the input to the pump, the output (Muffler) is still restricting the amount of air that can go through the pump.
Bur.........
If you were to replace the OEM muffler/(And maybe the CAT w a low Restriction Cat) with a low restriction (And louder) muffler.......you probably wouldn't gain much either.......but if you then put on a K&N muffler......the combination of low restriction input and low restriction output SHOULD be good for a few HP.
While it would be the combination that might add 10-20 HP (Just a WAG), most kids would say that the Muffler added nothing but sound and the K&N added 15 HP!!! (Or the other way around....the one you did second would be the one that released those hidden HP)

Some people say they have seen 3-4 HP gain by just putting in a flat panel K&N.
Well, I haven't done it lately, but I witnessed many a dyno run in my life and 3-4 HP is just the repeatability error you get on these devices.


Having said that I have run K&N most of the last 30 years.
They are reusable. I have often replaced the muffler (Such as that Miata I mentioned earlier).
I do not, nor will I, run a K&N on the Caddy.
Different kind of car with a different mission. I like it quiet.
 

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2006 DTS Lux III
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I agree with Southern. Putting a K&N on the DTS sort of goes against the Luxury aspect of the car. The K&N isn't going to help the air flow that much. The bottleneck is at the catalytic converter and the muffler. To change that would make the car loud. One of the pluses of this car is how quiet it is. The DTS isn't a sports car. Even the performance model while a little stiffer than the lux version is still posh and plush. It's not like a Lotus, a Honda S2000 or Porsche.

In some of the sports cars I've had in the past and on a sport bike that I had, I tried out K&N filters and didn't really notice any difference in mileage or power.

You really need to tweek everything to make a big difference, headers, intake manifold, valve size and timing/camshaft, muffler, cat. converter.

Just changing one item isn't going to make a world of difference. The system is only as good as it's weakest link. And to try to squeeze an extra 10 hp out of a big, heavy luxury car like a DTS doesn't really seem worth the effort.

I still want to know if that 34-36 mpg is a typo or in Canadian gallons or what...

Ciao,
Daniel
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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If you want to use a good air filter without the silly cost and bling of a K&N, look up a WIX for your car. Oil filter, too. They both have more media area, therefore less restriction. Google "knize oil filter study" and find the Knize Minimopar site (It's not a Mopar site) and read all the pro's and cons of different filters and who really makes them. You might be surprised.
 
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