"Worth it" to top off diesel for the winter?

[Martkimwat]

Originally Posted by valhalla360

But how much? 3 drops over the course of a winter instead of 2 drops?

If you look at how much water a cubic foot of air can hold, it's just not enough to get noticeable quantities condensing.

I wouldn't even trust the engine reps as this old wives tale has been around for decades and they probably were told it by the old reps and never actually ran the numbers.

It's not just the air that starts out in the tank, it's the fact the tank 'breaths' with every change in atmospheric pressure and temperature change. The larger the void, the greater the amount of moist air can enter the tank, which greatly multiplies the amount of moisture that can get into the tank.

[valhalla360]

Originally Posted by Martkimwat

It's not just the air that starts out in the tank, it's the fact the tank 'breaths' with every change in atmospheric pressure and temperature change. The larger the void, the greater the amount of moist air can enter the tank, which greatly multiplies the amount of moisture that can get into the tank.

If you read the whole thread, you will realize, the "breathing" issue is already accounted for in the estimates and even if you assume unrealistically high turnover and extract the maximum amount available, it is still a negligible amount of water that could be introduced via condensation.

[valhalla360]

Originally Posted by Celestialsailor

I won't even entertain you by opening that link but rest assured...you're right no matter what.

Perfectly played exactly in line with the skit.

[Dockhead]

Originally Posted by valhalla360

If you read the whole thread, you will realize, the "breathing" issue is already accounted for in the estimates and even if you assume unrealistically high turnover and extract the maximum amount available, it is still a negligible amount of water that could be introduced via condensation.

Indeed.

You have an image in your brain of air breathing in and out, and bringing in lots of water which "rains" down into the fuel. It seems plausible, and it is in line with generations of folk wisdom, and so a belief is formed. It gets embellished with atmospheric pressure changes, some made-up ideas about the role of fuel vapors, etc., etc., and the belief becomes stronger and stronger.

But this belief does not stand the test of actually doing real numbers based on a real understanding of how condensation is formed.


In the Middle Ages, EVERYONE believed that bubonic plague was caused by damp air. People reinforced each other's belief in this for centuries. Like condensation in boat fuel tanks, this belief did not stand up to the test of real science.

[TheThunderbird]

Focusing on condensation derails the conversation on the major issue:

Water is mixed into the fuel, for many a reasons... condensation playing a minor role.