I live on a gravel road 1/8 mile long, where I sometimes have to drive in gritty dust, coming and going ... it gradually rises up to coat my engine compartment with shiny grey dirt, rock dust. And when the engine is not yet warm, it's temperature sensor and valve directs air intake to be pulled up from the exhaust manifold area, down lower on the car's engine, closer to the dust coming up off the tires and road. Also there's a lot of pollen here in the Spring & Summer which helps clog it up. So I use upgraded air filter changes, every 10-15,000 miles, BEFORE I can actually see a lot of dirt on the paper. If I see some dirty areas begin to appear in the bottoms of the folds, for me it's time to change. I'm sure it's mostly nano-grit trying to get through. Maybe I'm obsessive but my 16-yr-old engine is still very tight, perhaps as a result of this and other upgraded maintenance intervals.

Some people claim that a filter can filter better when it's becoming dirty ... dirt captures dirt ... but even if so, it seems that also the dirty filter would begin to restrict airflow, increasing vacuum flowing into the throttle body at high rpms ... not good for gas mileage or peak acceleration. And how much of that dirt will eventually vacuum-migrate through the paper pores and on to the engine?

This paper filter is all that protects my well-maintained 165k-miles engine from sucking in granite sandpaper-like grit every day. I try and buy the most cost efficient, quality air filter for frequent change intervals ... and this Fram's gasket fits inside my 2.2L 4-cyl Toyota Camry's filter box like a glove. Together we can always breathe easy!
I live on a gravel road 1/8 mile long, where I sometimes have to drive in gritty dust, coming and going... it gradually rises up to coat my engine compartment with shiny grey dirt, rock dust. And when the engine is not yet warm, it's temperature sensor and valve directs air intake to be pulled up from the exhaust manifold area, down lower on the car's engine, closer to the dust coming up off the tires and road. Also there's a lot of pollen here in the Spring & Summer which helps clog it up. So I use upgraded air filter changes, every 10-15,000 miles, BEFORE I can actually see a lot of dirt on the paper. If I see some dirty areas begin to appear in the bottoms of the folds, for me it's time to change. I'm sure it's mostly nano-grit trying to get through. Maybe I'm obsessive but my 16-yr-old engine is still very tight, perhaps as a result of this and other upgraded maintenance intervals. Some people claim that a filter can filter better when it's becoming dirty... dirt captures dirt... but even if so, it seems that also the dirty filter would begin to restrict airflow, increasing vacuum flowing into the throttle body at high rpms... not good for gas mileage or peak acceleration. And how much of that dirt will eventually vacuum-migrate through the paper pores and on to the engine? This paper filter is all that protects my well-maintained 165k-miles engine from sucking in granite sandpaper-like grit every day. I try and buy the most cost efficient, quality air filter for frequent change intervals... and this Fram's gasket fits inside my 2. 2L 4-cyl Toyota Camry's filter box like a glove. Together we can always breathe easy!