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I wouldn't say that ALL bypass filters are significantly better than full flow:

A WIX 51515 (PH8A crossed) is a 21 Micron filter.

Used in CJ2s
Wix: 51006 32 micron
Wix: 51080 21 microns
Wix: 51010 32 micron

The standard C4 filter used by Chevvy in 50's trucks is not that great. Again, FRAM doesn't post specs but using a WIX 51006 is ONLY 32 micron!!!!!

You'd be better off with a PH8A and the PROPER installation than the original C4 or the modern WIX equivalent.

Modern specialty filters (AMSOIL etc) and even 50's toilet paper filters (frantz, etc) can get into the sub 5 micron range but with SIGNIFICANTLY DENSER media.

Any filter is better than no filter, though. Run whatever you can or change oil frequently.