This is a dated article (updated 1/08) comparing oil filters.

http://minimopar.knizefamily.net/oilfilters/opinions.html

Bottom line..stay away from Fram   

Motorcraft & Purolator Premium Plus are best buys at $3 

WIX and Purolator Pure One for $5-$6  

Mobil 1 is excellent but much more expensive. $10 

Thanks for the info Scott.  I knew about the problems with Fram filters back when we used to race stock cars.  They were known to blow engines through oil starvation.  I strictly use Amsoil synthetic oil and their filters.

IMHO, Amsoil products aren't worth the extra $$$  unless you are going beyond the normal service intervals and have high mileage applications. Neither seem to apply to our Cobras.

I think it's a small investment when you're talking about replacing a $12,000-$15,000 engine.

The $2 Supertech filters at Walmart are excellent filters too, believe it or not.  They're made by Champion Labs.  I usually use a good ol' Motorcraft FL1A for the Cobra.  The other heaps get either Supertech or Purolator Pure One depending on what I can find.

Just cut open a Fram and Purolator and can confirm results.   

But I love the grip on the Fram, but engine health is more important.   

Can't go wrong with factory filters. I use the Mann filters for the German cars and they are much better then what you can find in the stores. I usually get them here in bulk http://www.germanfilters.com/

FWIW, I had some issues with low oil pressure on the track car, esp when hot.  My engine is a 347, was running royal purple 10-30 and a wix oil filter.  Hot oil pressure at idle would be below 20psi, usually in the 17-18 range - just a bit low for my liking.  On track it would run mid-40's...  I run an oil cooler in the nose, with AN10 lines.  The cooler has 1/2"NPT fittings, it was rated to handle 500hp, more than my engine produces.  I thought I'd swap filters, see if that helped the oil pressure, and it did.  I went to a K&N filter, and saw about a 7-10psi jump across the board - hot idle around 25, on track pressures around 50.  Same oil, etc...   This may indicate the K&N doesn't filter quite as well, but it's apparently not as restrictive. 

This may indicate the K&N doesn't filter quite as well, but it's apparently not as restrictive.

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Sounds just like their air filters too...

On the street it may not be too much of an issue but I came from the Jeep world and saw many, many examples of copious dust in the intake tract on vehicles that used K&N air filters - mine included. I went back to a factory air filter after that.
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