Oil Filters...Smaller vs. Larger

[Bluestone]

Any thoughts about the newer smaller oil filters being less efficient than the original larger ones? Think that they're good for 3k miles of effective filtration?

Or would you just go for for larger filters instead?

I'm focusing here on non turbo applications.

I would think that for turbo engines, the smaller filters give only marginal protection.

[GeneralDisorder]

The old school ideas about larger filters being better are outdated and incorrect. First there is the fact that the filter is inexpensive and is being replaced with the oil every time. Subaru used to reccomend the filter only be changed every 15k miles. With a 3k or 5k interval you simply don't need all that extra filter media. Also - to a certain extent the filters actually improve with age and will filter to a smaller micron rating as they trap particulate.

 

As for the OEM filters on the turbos.... They have not been an issue. I have a friend with an '06 STi that has over 90k on it - Mobile-1 synthetic and oem filters. Been rallied hard and has even survived a cracked pickup tube. Runs like a top and you couod eat off the internals.

 

GD

[nipper]

If you have the room and clearance a larger high quality filter will do no harm as long as it has the same specs. Anything you can do to add oil capacity is a good thing.

[GeneralDisorder]

It really depends on how they are designed - a good quality filter will start out (brand new) being able to filter particulate down to about 15 to 20 micron at near 100% efficiency (usually listed as 99.9%). But as they age and these larger holes start to clog up with bigger particulate then the micron rating of the filter *improves* by a decent amount. Studies have shown that wear reduction can be acheived by filtering particulate as small as 10 micron. Even most quality filters will only acheive about 85% filtration at that small of a particulate size when new. As they age however, they become better at filtering and can raise that percentage.

 

The length of time it takes for a filter to acheive it's smallest particulate filtering size and reach the "plateau" where it will stay till it really begins to clog up will get longer the larger the filter being used. This is the undesireable effect of having too large of a filter or of changing it too often.

 

A better way to improve your oil capacity and dramatically improve your oil life is to install an oil cooler.

 

GD