The G Man

Just bought a 05 GX with about 50 miles on it now, too early to tell what the MPG is yet.
Just wondering if anyone on this forum have use a K & N air filter for their GX. I had one in my old MDX and it increase gas mileage by about 5%, I am thinking about putting one in my new GX.

Donger

There are a few posts in the forum recently about the K&N. I just ordered one for my '05.

I found most on-line stores don't list one for the '05. Lexus parts tells me the '04 will fit the '05 (as well as the 4Runner and Sequoia). Hoping to see some slight improvement (and hoping it really fits )

I, like you, had one on a previous vechicle and saw maybe 1-1.5 mpg improvement.

T_standard

for the first 5000 miles or so you will experience some subpar fuel efficiency

Donger

Good and bad news on the K&N - the '04 filters fit the '05 just fine; that's the good news. Ran my first tank with it installed at got a huge 0.3 mpg increase; not what I was hoping for. But, the engine is still a bit green with only 5800 miles and this just one measurement off one tank. I am hopeful to improve that over the next few tanks. I read somewhere that K&N's get more efficient with a little dirt in them. I don't know why that would be - anyone else hear this rumor/myth?

The G Man

I put in a K&N filter in my 03 MDX at about 20000 miles and saw a 0.7 to 0.8 MPG increase which is about 5%. The MDX's MPG was still climbing up to about 8000 miles before it leveled off. My new 05 GX is getting about 15.5 MPG right now using premium gas and a mixing of 50/50 highway city driving, I think I will wait till the GX hit 10000 before I change over to K&N.

loflin

I'm almost hesitant to add my $0.02 worth, as I don't want to get bombarded with all the anecdotal stories from aftermarket filter proponents.

But here is my thoughts...

IF you want to buy an aftermarket filter, by all means go ahead. If it's a lifetime AND you maintain it, then it's a good deal, etc.

But as far as MPG increases here is a couple of things to think about:

K&N, nor any other reputable manufacturer make NO claims anywhere in writing about MPG increases.

More importantly, Car manufacturers are PENALIZED for not making certain overall "fleet MPG" numbers. This either ends up with an actually penalty paid, or they are forced at the end of the year to adjust their sales mix, limiting sales of low MPG makes, which potentially costs them in sales.

Finally, the Car manufacturers invest A LOT of $ in improving MPG designs (while meeting the emission requirements).

So I would think that if they could improve their MPG by something as simple as putting a different air filter, I'd think it would have been done. IMHO

AgentWD-40

That assumes that the engineers get to run the show. The bean counters might get involved and not like the added cost of the air filter. Filter A might cost $0.50 and filter B might cost $3.00. That is a lot of money over a million units. Overall I agree with you though, it seems like a simple way to make an improvement.

I also wonder if I'm letting in extra air am I letting in extra dust and dirt?

loflin

Yes the bean counters count, but it's not as simple as just counting the piece part cost. Additional MPG (or HP rating or whatever) is also worth something. Both in advertising, but also for MPG: real $, as described above in fleet MPG requirements.

If only piece part cost was costed, then you would have never seen 3 and 4 valve per cylinder designs, as an example.

The G Man

If that is truly the case, then every car and truck made would be either a hybrid or diesel.

loflin

Sorry G Man, I'm not following your point...

Where talking a couple of dollars on a filter, not thousands of dollars.

But to your example....Eventually (i.e. 10 or 20 years out), every vehicle WILL be some form of hybrid, IF the government continues to raise the fleet MPG requirements. Even though hybrid design will raise the cost. Which is the point I was making: Auto makers will spend the $ in cost for "benefits" that justify the cost overall (justify as in increased sales, increases prices, reduced government penalties, etc.).

CivicFerio

You guys should check out this air filter test. It's quite interesting.

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

The G Man

Very interesting reading, according to this data, it seems like a plain old $5 AC Delco air filter beats out everybody. I actually did some more research on independent lab test of the K&N after I read the above article and found more evidences supporting that article than against it. This sure shed some new light on the matter. I am wondering if the increase in MPG I experienced was just due to the fact that I had a new air filter installed. Seems like the safest way to go is to change out the OEM filter every 10000 miles.