Question about used air filter

K&N filters are a gauze or cloth material so they will stand up to washing. Paper filters are just that, some have a slight wax content to trap dirt but no matter what when you wet paper sooner or later it falls apart.

Unless you live in a dust bowl changing filters every 5000 miles isnt needed. Do it once a year unless you are putting a lot of miles on. I find up in the New England area that the dust from the road chemicals and sand in the winter collects worse than dust in the drier months. I change all my vehicles air filters each spring after the roads have cleared with the spring rains.

I put the used filter in a bucket of water with some detergent and let it soak for a while before flushing and drying it. My question is as follows:

The old filter now looks clean, but has it somehow "lost its filtering powers" in the abovementioned process?

I know K&N make a big deal about their filters being washable, but as far as I can tell, so are the cheap paper ones.

So as long as the filter isn't falling apart (it stands up against the pressure from a vacuum-cleaner) it's OK to re-use?

Yeah, I know. It was done in the process of trying to get better milage. Turned out that the fuel gauge was the problem, low-fuel warning light came on with aprox. 30 ( of 74 ) liters in the tank.

Of course not. Air filters load-up with dirt long before they physically begin to break down ("fall apart").

The rule with a proper OEM-type "paper" air filter is if you can easily see sunlight or the light from an incandescent household bulb through the filter when you hold it up to the light, it's OK. If not, replace it.

DS

Yes, but this used filter had been washed, and most of the dirt (apparantly) went with the water. You can see sunlight through it.

Sunlight? Maybe the answer to the OP's question is, can you see sunlight through a New Filter? - RM

Throw it away. "Paper" air filters cannot successfully be washed. When they get wet, the "paper's" structure changes so it's no longer an effective or efficient filter. This is not just writing paper we're talking about here!

DS

____Reply Separator_____ Huh? What does the low-fuel light coming on have to do with gas mileage? Fill up the tank, divide the gallons to fill up into the miles put on the vehicle since the last fill up. It doesn't matter if lights come on, bells ring, whistles blow. They have no effect on miles per gallon.

Yeah, I know. I *thought* I had poor milage beacuse of the warning light. The air filter seemed rather dirty so I just replaced it without checking the actual milage like you describe. I could buy around 10 air filters for what a tank of gas costs here in Norway. I ended up with 0,137 liters per km on mixed highway and city driving, which I found acceptable for a '78 lebaron.