STP Air Filter Efficiency

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I watched my cousin changing the air filter in his Jeep using an STP filter.

The box said 90% efficiency. That struck me as very low. Shouldn’t it be in the high 90s?
 
90% efficient at what? Filtering out gravel sized chunks? Unfortunately, there's not a lot to go on here.

However, this is likely a case of where your cousin got what he paid for... or less than he paid for.

I can buy a $3 oil filter, and see the spec is 99% at 30 microns... right on the box. For what I'm trying to accomplish, that's plenty good enough.

Air filters may not be as straight-forward.
 
Originally Posted By: JerryBob

The box said 90% efficiency. That struck me as very low. Shouldn’t it be in the high 90s?


Not enough information available to make an informed decision.


Yes, really.
 
The only way to know is to query the manufacturer. That is an odd spec to list given that other manufacturers list higher numbers. It wouldn't be a horrible filter if it was a test made on find dust. That would equate to somewhere around 95+% on coarse (which is the more common spec listed. Nowaways, most mfrs list 98 percent on the coarse dust test and some at 99% (one percent counts for a LOT in an air filter and 4-5 percent is HUUUUUGE). 90% isn't much better than an oil bath filter and they suck (literally and figuratively).
 
Sadly, this number sounds not good to me, though we don't know what the 90% efficiency rating is for. Sadly, this is the only filter I can get locally for my 85 rx7. Everything else has to be ordered online and Fram has pretty much stopped making that filter so you can't get it anywhere.
 
I run 2 STP filters on my DD 83 Silverado with no problems, oil and air get them at AutoZone.
thumbsup2.gif
 
Yeah I saw that the other day in AZ. And I was like holy cow that is substandard.

I thought the back of the box should have read: "This air filter only catch large insects, hummingbirds, and large pieces of gravel. This air filter is not intended for the meaningful use of small particulate filtration".
 
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Purchased a STP filter for my 2008 Jeep Rubicon the other day. The rubber seal around the edge of the filter is not even secured to the filter media. Pulled the seal loose removing the filter from the box. Took it back and purchased a Purolator filter.
The STP is a very poor quality build as far as I am concerned!
 
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