So I decided to shell out $50 a pop for K&N drop-in air filters for the Cobalt and the Colorado after reading a few Cobalt owners report some mpg and hp gains after replacing the conventional filter. I won't get to do the installs till the weekend (when I also do the fuel filter on the car) but have any of you experienced any worthwhile increases in power or economy from one of these filter?

If nothing else, they'll pay for themselves over time since they are reusable.

I can't speak for fuel economy, but you should notice a seat-of-the-pants difference. K&N filters are much more free flowing than paper filters, allowing the engine to breathe better.

oh hey, i am very interested in hearing how it turns out on the cobalt. i like the zippiness of the cobalt but anything that can uptick the mpg these days is worth a look.

At issue with the oiled filter debate is how (and how quickly) air flow deteriorates when they start accumulating dirt.

I've read more than 1 in-depth review of air filters and while the K&N does have better flow when first installed, it quickly drops below the air flow of a conventional paper element. And unless the policy has changed, K&N recommends a 50,000 mile interval between re-oilings- which gives it a long time to accumulate layers of oily dirt. IMO, it seems K&N and the others have over-extended themselves in trying to present a 'double whammy': better performance and a much longer service interval (to help justify the price??).

Before this research came out, I ran one in my Ford. Very tough to tell if there was any difference from it alone; I had installed it in conjunction with a mild chip (15HP/30TRQ). But since then, it's paper elements only. Over the life of a conventional filter, a quality conventional filter will average better flow than the K&N.

Edited February 16, 201115 yr by balthazar

I never noticed a difference in performance or mpg in either the Cutlass or CTS (both DOHC that should benefit from easier breathing). I would clean and re-oil the filter element at the standard paper filter change intervals. In my mind, it was still going to collect about the same amount of dirt over time regardless of the type of filter element I used

^ Very logical.

Yes; one could clean/re-oil the K&N at much more frequent intervals than 50K (I would), but what service interval it would take to keep the K&N flowing at peak performance is anyone's guess.

I agree with cleaning it at regular service intervals of paper elements. With that said, the recharge kit costs a nearly half the price as a paper element, so it will still pay for itself.

I forgot to mention that my experience with a K&N filter was also with a CAI setup. I don't know how much a difference you'll feel with a stock intake.

K&N recharge kit is around $13- paper air filters aren't commonly in the $20+ range (tho I don't doubt there are ones marketed that high & higher).

Last one I bought i believe was around $6.

You get multiple uses from a recharge kit, probably the lifetime of the filter if following the schedule I mentioned

^ This, I know : I did say I ran a K&N (for at least 7 years), and I cleaned it around 30K (vs. the recommended 50K). I did not go thru 1 cleaning kit.

You can get a paper filter in the $6 range, whereas the K&N I bought was around $50. So for the $63 paid up front to run K&N, you can get 10 years worth of annual paper filter changes. If there was a measurable performance difference, if your performance is a matter of minute advantages (IE: on the track) you're getting something for your money. If the performance is basically the same, where's the benefit? If performance is worse after a short timespan, you're getting ripped off.

Increased airflow is still the reason one switches to these, and the testing I saw refuted the claim after less than a conventional filter's normal lifespan. I can tell you this- the diesel truck crowds' consensus is 'stick with conventional'.

I wonder if I can get my Toronado from 140hp to 143hp with one. It's just about the worst breathing V8 ever.

If you want to save money, just stick to conventional paper filters but change less often. CR and DOE both have done tests concluding that dirty filters, while having a tiny effect on performance, has no effect on fuel economy for modern vehicles.

Did the fuel filter and put the K&N on the Cobalt tonight when I got home, after seeing how easy it was to change the fuel filter without even jacking the car up - all I needed was an $8 "quick disconnect" tool. There's definitely a seat-of-the-pants difference, but unfortunately I can't say how much of it is due to the K&N filter because I did the fuel filter at the same time. However, the gas that came out of the old filter was essentially clear, and I can see right through it so I assume no clogs. I'll be better able to gage the effects of the K&N on the Colorado tomorrow, as I plan on putting it in after I come home from a bike ride.

Either way, I'd love to hit 30mpg city in the Cobalt this summer (I'm usually at 28-29 in the warmer weather) and 20mpg city in the Colorado, which has given me 17.5mpg city ever since I got it.

Still like the paper ones...just something that I don't like about the oiled part.

Might consider trying one though.

My Cobalt has a K&N filter. I'd like to have gotten the entire intake, but it was over $200 ... yeah, maybe later...

Anyway, I think it had lost some power since it was brand new, as engines do over the course of their life, but there was definitely a noticeable difference in acceleration/onramp merging performance, and fuel economy. After a few years I was struggling to get 25mpg in town under normal (for me) driving, but now it basically gets the same mileage it did when it was new: 28-29 in town, 35 on the freeway.

For those is you who have run it for a while; How often do you maintain your K&N?

TJ, that sounds like a worthwhile difference. I had one in my '04 Colorado, maybe next month I'll spring for one in this one.

Yesterday, I came home, changed the filter, and went right back out again. It made a much more profound difference on the truck than it did the car, possibly because the Colorado intake is not all that restrictive (relative to the Cobalt's. The K&N realy opened it up. It's noticably quicker off the line and seems to have more oomph throughout low and mid RPMs.

Yep, it's good stuff. At a Meet a couple year's ago a friend put a J-Intake in his car. LH's have pretty restrictive intakes. A forum member builds custom col air intakes (even paints them to the color of your choosing) and puts a K&N cone filter. His setups costs half the price of K&N's CIA. I went for a drive with him right after we got done installing it and it made a big difference in response, as well as sound.

IMO they're worth the cost of admission.

The question remains- how it performs vs. paper once it starts to accumulate dirt.

They have been proven to outflow paper when brand new- that's not the issue. They have far less filtering area that their equivalent dry filter.

Here's some LS1 folks with feedback :

http://www.ls1tech.com/forums/generation-iii-external-engine/158472-air-filters-oiled-vs-paper.html

In this day & age, with decades of heavy CAFE pressure on the neck of manufacturers, if an oiled filter would outperform, better the economy & outlast a paper one over the paper filter's lifetime, manufacturers would use them. They could make them themselves for $2/ea.

Edited February 21, 201115 yr by balthazar