[Sirrotica]

The full flow filter could be removed from the engine and blocked off, and the by pass system would do the same job as always, keep the oil clean. At one time Frantz did actually sell a plate to eliminate the full flow filters. To answer your question the same full flow filter is on the engine that was on it when I installed the by pass system. I'm not worried because just as you surmised the by pass filter runs all the oil through it in less than 10 minutes. You'd have to have some major problem to generate more dirt than the by pass could remove every 10 minutes. A problem that bad would be terminal for the engine anyway.

If the full flow would ever clog completely (not likely) it would open the by pass valve that the factory engineered into the full flow system, and the engine would be supplied clean oil even though the full flow was clogged. The full flow filter is not even necessary if there is a by pass system in place. The older automobile engines, the filter was a factory option. You could order a car with or without a canister filter. Just an FYI, the optional filter was a by pass style filter. The full flow system was yet to come, and it was a much cheaper system than the by pass canister system was.

Diesel engines do get more contaminants in the oil due to the high compression ratio there is much more blowby and contaminants getting into the engine. All engines however when run produce contaminants that get into the oil, removing all of them ASAP is paramount for the engines as well as the oils health.

The VW air cooled engines only had a screen in the pan, no filter whatsoever. When VWs were being converted into dune buggies (60-70s) the engines weren't lasting long in the desert sand dirt and dust. The hot rodders soon found that using the Frantz filter on the VW engines extended the life of the engines considerably. Most VW fans know that the Frantz filter or some type of by pass filter is a definite need if you want any kind of reliability in a VW air cooled.