Back in the 70's I spent some time refitting LARC's. These had a 19 odd litre Cummins V8, couldn't tell you the model. I never touched the engine, other than crawling around it to get at other things, but I can tell you they leaked. The Army, being the Army, went as far as fitting new (? Might have been rebuilds ) to some, but it made no difference. We didn't have many of the things, but I reckon the 30% ratio would be about right based on what I was able to observe from my lowly viewpoint and dimming memory.