Which should I go by. I just replaced my Fram engine air filter with a new one. It said to replace at 12K miles. Toyota manual says to replace air filter at 30K miles. I did the replacement because the reminder I had set in the car expired and I believe the reminder was 10K.

Ideas?

 

It really depends on the service conditions. If you drive in dusty conditions, the air filter will need to be replaced more frequently. If your driving is in clean air, the air filter can go farther.

You can inspect air filter periodically, and change it when it looks like it needs to be changed. Remove it from the car, tap the debris out, or blow it out with compressed air, and then look at the filter. If it looks clogged (dirty or discolored), or if it is damaged at all, then change it.

Or, you can change it on a schedule, depending on the service conditions. I live in Florida, were there is very little airborne dust, so I usually change mine once a year. In a place like Arizona, it would need to be changed more often.

When in doubt, change it. Filters cost less than engines.

 

"..then look at the filter.."

Look THROUGH the filter holding a trouble light on the other side.

 

neither. invest into K&N or other reputable (are there any others though?) high air flow filter.
1. improves mpg
2. good for 1 000 000 000 miles
3. 10 bucks worth cleaning kit will last you through at least 3 cleanings/charges
4. cleaned every 50 000 miles.

beat that with any regular filter. now, this post will be followed by avalanche of "K&N is bs" responses. and that's fine. except that I know 100% it does improve mpg. firm it's well worth 40 bucks I paid for it. so firm, I have ALL of our cars converted to K&N as soon as we buy one.

 

Where do you live jpezz? I tend to accumulate a considerable amount of dust in my air filter during normal driving so I replace mine every 25,000 miles or so. Sometimes all you have to do is remove the air filer element from the housing and knock loose the encrusted dust/dirt particles and reinstall the filter. I find that this is a bit more of an economical approach than replacing the filter whenever there's easily removable dust on it But then again I'm a cheapskate so what do I know

I agree that K&N is a reputable brand and can personally verify that you will see improvements in fuel mileage if you install a unit in your car, but for people on a strict budget the OEM filter should suffice. I buy mine for just $13 and they last for a year or two so you really can't argue with the value element there

 

"..I know 100% it does improve mpg.."

Do you really spend that much driving time at WOT...?

99.99% of the time the throttle plate itself is the MAJOR restriction to intake airflow. So yes, for most of us for that remaining .01% mpg could be improved via a K&N "snake oil" filter/kit.

But then don't forget that for each time you have to clean and re-oil the K&N you MUST have cleaned the the OIL and DUST covered MAF and IAT sensor elements at least 2-3 times.

 

"..knock loose the encrusted dust/dirt particles..."

That's fine but it's the tiny, microscopic, dust particles that get EMBEDDED within the "mesh" structure of the OEM filter that become the major blockage to airflow.

 

Air filter really have little or nothing to do with engine efficiency. They are basically just to keep gravel from getting into your engine and killing it. A single large piece of gravel can kill an engine almost immediately, of course. Small pieces of gravel (aka, "sand") can damage the valves and score the cylinder walls, and shorten the life of the engine. As long as the engine gets enough air, and not too much gravel, it will be ok.

The oil-coated mesh that some companies sell as "reusable" air filters, do not stop fine sand. They do emit oil, which then coats the air-flow and air-temperature sensors. The sensors may then need to be cleaned or replaced to function properly. Bad sensor readings from oily/dirty sensors are very likely to adversely affect fuel economy and system performance.

Engineers developed pleated-paper filters about 100 years ago for a reason. Every car manufacturer recommends them, for the same reason. That reason is, of course, that the oil-based filters which were used previously, allowed too much sand to get into the engines, and caused too many premature engine failures.

Paper filters are cheap. For every $2000 that you spend on fuel, you might spend $20 to change the engine air filter. Add a cabin-air filter, and a couple of oil&filter changes, and you still won't even spend $200.

Filters cost a lot less than engines, even if you pay the stealer to install them.

 

K&N filters have good marketing strategy, they are like MONSTER cables in Best Buy. If not done properly you could put too much oil in the filter and mess up your MAF sensor (and this sensor is not cheap)

Cold Air Intake has been a debate in most car DIY, the gain in MPG is completely nil because an increase in horsepower (if there is) tends to press the pedal more, negating the benefit. It's not all about MPG, it's the throttle response.

I'll stick with ordinary filter, change it often as they're not that expensive.