oil filter questions

[wtb853]

An oil filter that came with a civilian L134 was leaking through the box on my parts shelf. I decided to take it apart and drain the last bit of oil out of it. I did a little research after disassembing it and found out it is a mid-war GPW oil filter. I would like to trade it for a correct M38 oil filter either here or over on g503.

My question is what is the correct oil filter for a Jul 51' M38? I referenced pages 21, 22, and 43 in ORD 9 snl g-740 as well as page 54 in Ryan's book and can't discern whether one superceded the other and in what order. I also referenced the photo gallery here and saw examples of both types.

Are there any advantages/disadvantages to the Cuno vs. Fram?

For reference the filter I have says:
MILITARY STANDARD FILTER
COVER ASSEMBLY 25791 PUROLATOR PRODUCTS INC
There are remnants of a red sticker on the side. The numbers 27078 and 2680? are visible.

[ocwd]

The original would be a cuno oil filter. I think that the Military Standard is a correct replacement for the cuno so it's not a big deal unless you are trying to do a factory class restoration. I do not know too much about MB/GPW but your Purolator may be worth more than a cuno filter. I bet most of the venders have NOS Cuno filters.

[magnum]

Wes,

Did some of the later production M38's come with the canister type filter? I have heard that the last 600-800 produced came with the canister type.

Thanks.

[dayboy42]

NOS cuno filters are plentiful and cheap! Either type isn't going to filter much... the systems are not designed to filter the entire system like our cars today.

[wesk]

The ORD 9 has a few errors.

1-The six pre-production Pilot model M38's had the military junior oil filter.
2-ALL production M38's and early M38A1's had the Cuno filter from Willys factory.
3-M38A1's after serial MD28132 (Oct 52) had the military junior.

Either type isn't going to filter much... the systems are not designed to filter the entire system like our cars today.

This is a very common misunderstanding of how a partial flow oil filter system works. It only has part of the oil passing thru it at any given time but eventually 99% of the oil will find it's way thru the filter. Agreed this is not the same as modern automotive full flow system but it has about 90 % of the modern system's capability and is certainly a lot better than no filter at all.

[wtb853]

I caught a comment on the g503 site about "sacrificing the life of an L134 using a Cuno filter for cosmetic reasons" from Wes's adversary. It sounds like the military junior fram filter was used exclusively as a replacement for the Cuno filter. There must have been a good reason. I searched 6 or 7 old threads on this site talking about the Cuno, but never saw it definitely stated that "the Cuno was substandard because........."

Does the fram filter protect an L134 better than the Cuno? Or was the Cuno replaced for another reason (cost, maintenance, etc.)?

[Ryan_Miller]

[wesk]

Don't believe everything you hear.

The CUNO filter has been serving the auto industry, the aviation industry and industrial equipment industry very well since the 1930's. They still are producing Cuno filters today.

There was never a major drive to replace all the Cunos with Juniors. The Army simply stopped stocking two different filters so if your Cuno required a replacement part the part was not generally available then supply substituted a Junior filter assy.

I still use them. I have aircraft customers still using them and their engines cost upwards from$25,000 to overhaul and their engines make their scheduled TBO's with no problems using Cunos.