I do not think there is too much pressure at the cap. Have you even taken the drain tube apart? The middle juncture is tiny, with a very small o ring and it just snaps together with the deeper section of the drain pipe. The cap itself is also pretty "weak". In other words, I do not think there is tremendous amount of pressure going through that area. There might be some, but not a lot. Although not adviced, I heard of people removing the oil cap while the engine is running. They lived, so the pressure must not be too high.