Oem or aftermarket oil filter?

From jan@lipari.usc.edu Thu May 18 17:15:09 EDT 1995

I dissected a VW and a Fram oil filter a little while back. These are the differences:

  1. VW filters (made by MANN) had a more rigid casing. There were also more welds to hold the casing and the top together. This is important as oil pressure may blow the oilfilter appart. (Uncommon, but known to happen [Recently several cases were reported on Corrados G60s & Porsche 944s where the FRAM filters ruptured or the seal gave way, destroying the engines. Factory warrantee was voided, the person in the 944 however won a case against FRAM].
  2. VW had two spring loaded valves (anti backflow & bypass) while FRAM had one spring loaded and one rubber membrane type valve. The anti-backflow valve will prevent retain most/some of the oil from draining out of the engine, thereby supplying the engine with hard needed oil immediatly at start up. Presumably, the springloaded anti-backflow valve will do the job better then the rubber membrane. The bypass valve alows oil to bypass the filter when the filter is either clogged or too viscous. I read somewhere else that the FRAM's bypass valves are sometimes set too low such that no filtering ever happens.
  3. The parts to which the ends of the filter element was attached were metal in the VW filter and cardboard in the FRAM filter.
  4. The pleats of the filter element were neat and regular in the VW, croocked and held together with a little string in the FRAM.
  5. How the actual filtering compares, I don't know. According to Consumer Reports, they are similar (but the rest ISN'T).

Other case in point:

A friend with a Mazda truck experienced rod nock with FRAM filters at start up. Upon consultation with Mazda, he switched back to Mazda filters, which solved the problem. Presumable the afforementioned valves are to be blamed.

In article db36+@andrew.cmu.edu (David Stuart Bridge) writes:

I recently heard some talk at my mechanic's garage about using only Mitsubishi oil filters on Mitsubishi engines. Apparently, use of non-Mitsubishi filters can cause some real problems -- some guys said they came accross engines that were blown because of the "wrong" filters.
In general, I found the FRAM filter of significantly inferior construction compared to the filter I normally use [on VWs]. The above was enough evidence for me not use Fram filters (or most other brands) for my car. It's worth the small $ difference to me. (I buy my VW filters on the rare sales some of the dealers have, in which case the filter cost me about US$5 (vs $4 for FRAM). I used to be able to get MANN for about that much as well through Beck Arnley, but since they merged with World Parts I have had trouble finding them [and haven't really tried either]).

Your [non-VW] car might be perfectly fine with Fram filters if the original equipment and the Frams are similar in construction. Your OEM filter may not require these valves. If you want to be sure, get a hacksaw and see for yourselves. [It's a big mess if you use used filters though. Let them first "drain" overnight].

Jan.