PassageMaker - May/June 2011

LETTERS TO THE EDITOR

have been told to change the oil in my car every 3,000 miles, even though my owner’s manual suggests 7,000. Is it really necessary to change the oil every 100 hours? I would prefer not to do it when we are under way and hundreds of miles away from our home port and the facilities we know.

Ed Kuzan Buffalo, New York

Oil replacement can be a tricky pseudo-science. How long oil remains within manufacturer specifications is largely a function of the condition of your engine and how it is used. Engines that are routinely underloaded (running most of the time below 50 percent load) often have increased fuel and soot contamination in their lubricating oil and therefore benefit

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from more frequent oil changes.

Provided your boat’s engines are in good tune, 100-hour oil changes are very conservative and probably overkill. However, if you are storing your boat for the season, then by all means, the oil should be replaced before the storage period begins, regardless of the number of hours on the engines. (Because used oil is acidic, it’s undesirable to keep it in a stored engine.)

If you are fortunate enough to operate your boat year-round, you can probably go 150 or even 200 hours before needing an oil change. But don’t guess—for about $25, you can have your oil analyzed by a lab. Do this at 100 hours and see what the lab says. If the oil remains usable, then go 150 hours and sample again. You can repeat this process up to 250 hours. If your oil remains usable, then you know that, barring an engine problem, it’s probably safe to go at least this long in the future, provided your engine loading and usage habits remain constant. Thereafter, I would carry out an oil analysis at each oil change.—Steve D’Antonio

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BILGE BLOWER REPLACEMENT

I am replacing my boat’s old bilge blower with a new one. The old blower is on the exhaust side of the tubing, and that is where I will place the new unit. I am curious, though, as to why boats do not also have a blower on the input side of the venting to force more air into the engine room for compartment cooling and to supply air to the carburetor. Is it dangerous to have a blower on the input side, or does it simply not produce noticeable results?