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I cannot see how you can state that you are certain I installed the seals wrongly the first two times when I followed religiously the "amel way" and ended up with water in the C-Drive oil within two years of use.
Also, I don't think that your answer to the water vs oil is so obvious: having salt or dirty water in the transmission is not good and certainly worse than having the level of oil drop by a few mm with can be topped up. In fact, it is recommended to check the level of transmission oil as much as the engine oil level before each engine start!.
But let me be clear: lubricated SEALS DONT fail catastrophically and certainly not 3 at a time.
Stating that I will only know about oil loss when the C-Drive meltdown is the same as saying that the C-Drive oil could be completely replaced with water while you are motoring along; IT JUST DOES NOT HAPPEN.
The most important finding of my experiment was that the loss of oil ACTUALLY stopped AFTER I added an additive to the oil that effectively made it heavier. It was the same additive used for old engines to prolong their life before full repair. Not only I had no oil loss during use the last month of the season, and during the 5 months winter layover, but while the boat was hauled out and I waited for the bushing to arrive (5 days), there was not a single drop of oil out of the shaft !!
That tells me that even though there was wear on the outer seal and bushing surface (see my pix in facebook) and that wear initially allowed some oil to escape after more than 4 years of use, when the oil was thickened, the seal began to work again and my guess is that it would have worked for a long time since it was now being lubricated in reverse due to the bushing wear.
Also worth adding is that when I drained the oil from the C-Drive, it was as good as new. This is to be expected since, unlike engine oil, on the C-Drive the oil is not exposed to combustion materials and heavy temperatures and remains viable as long as no water leaks in.
But, to avoid further discussion on the mater, let me be clear:
I AM NOT RECOMMENDING TO SERVICE THE C-DRIVE EVERY 8 YEARS.
I am just saying that "the amel way" for this particular issue can be improved and my experiment demonstrates it without any doubt.
Personally, I will continue to replace the seals and oil every two years, or when the boat is wouled out but I am pretty sure that I will be able to reuse the bushing a few times, particularly after I have it chromed and I will continue reporting my experience in this forum.