I have to disagree, even with Tom Langdon, on this one. He told me that, since a bypass filter only filters about 10% of the oil, leaks will be more of a problem than any benefit that a bypass oil filter can provide.
My viewpoint is that any filtering is better than none. Don't plan on extending oil change mileage because you add a bypass filter, but, if the engine doesn't produce more crud than the filter can take out, it may take ten circulation cycles, or more, to get the crud out, but eventually most of it will be filtered out.
I have a '51 4400 and a '50 3800. The 4400 had the add-on bypass filter and the 3800 didn't. One confusing factor is that the 3800 also has the valve cover with vents.
I pulled the valve covers off both and took pictures. The 4400 valve gear looks nearly new, even though it hasn't been run for more than 12 years. The 3800 valve gear is filthy with multiple dirt encrustations. (It has been run for more than an hour since I bought it.)They have nearly the same mileage on them and both odometers work.
So, you decide.
