größerer Ölfilter

Quite simple: A large capacity oil-filter naturally contains more oil than a small one. That means the total volume of oil in the system increases as does the oil filtering capability. Clearly a larger circulating volume of oil gives better engine cooling. Better cooling means less engine wear. Less wear means a longer live for your motor. An longer living motor means pleasure to you.
Finally that all means: A bigger Oil-filter brings you joy.

This images show you the comparison between the normal and the large capacity oil filter. The large filter cooling surface and its capacity decreases the oil temp. on the order of 5°C to 10°C.

Many 2CV-engines suffer from too high oil operating temperatures. This causes severe engine wear and may even lead to a piston seizing. This usually marks the end of an engine's life. Oil temperatures above 110°C (230°F) are not rare but not good for your 2CV.
But there is an easy and inexpensive way to improve your motor's life.
Install a large capacity oil-filter. Its large surface area dissipates a great amount of heat or, the larger the surface area the better the cooling. The filter works as a supplemental oil-cooler, one that is not as efficient as the principal oil cooler but it contributes significantly. Additionally, the increased oil capacity lowers the oil operating temperature because the oil can efficiently 'store' the heat, but outside the engine. The more oil the better, an axiom we know well.

With many cars you simply need to replace the original oil filter with a larger capacity filter from some other application.
But a 2cv would not be a 2cv if it would be just that easy. Unfortunately, there is no oil filter that fits the threads of the 2CV engine. At least no oil filter that is larger than the original filter.
So you have to change the 2-CV mounting threads to a more common thread size.
After this you can obtain a suitable large capacity oil filter at your auto parts store in whatever size you want.

I will alter the oil filter-mounting for only 28.-EUR. Simply send me your original filter mount and I will convert it and return it to you within a few days. I will also provide you with a large capacity oil filter for an additional 11.- EUR. You need not visit a car parts store for this item. In the future however, you will be able to obtain the desired large capacity oil filters in any car part store. A much better situation than for the original 2cv equipment.