The well-supplied engine

When voyaging, your boat’s diesel engine needs a steady supply of oil and filters

An ocean voyaging vessel is first and foremost a very small cargo ship. It needs to transport you and all your worldly goods safely and efficiently to where you wish to go. Yes, sailing ability is nice, comforts are nice, looks are nice, entertainment is nice, but you aren’t going far if you can’t carry sufficient food, water, and gear to supply your needs on the trip. And for many of us, an important part of moving this cargo is the auxiliary engine, which in turn needs its own supply of essential consumables, parts, and tools to maintain its functionality.

The volume of supplies required by the typical auxiliary diesel engine can be significant: oil, filters, transmission fluid, coolant, grease, other lubricants, sealants, spare parts, and specialized tools. A balance has to be struck between carrying sufficient supplies and the amount of total storage space on board the boat, and you have to tailor what you bring to the nature of your voyage.

In this article I will discuss the first category on this list, which is the essential lifeblood of your engine. Even if you do nothing else to keep a diesel engine running well, you must supply it with clean fuel, clean oil, and clean air. Providing those three essentials probably means a long and productive life for your engine. Let’s see how voyagers can manage the procurement and storage of these items.

Oil, oil everywhere: Stage 1
A trip up and down the East Coast of the U.S. or around the major countries in Western Europe will inevitably have you passing close to many marinas and other stores where supplies may be purchased, so your storage needs will be much lower than someone headed to Labrador or the South Pacific. However, one can never count on finding just what you need exactly when you need it. It is therefore prudent for every boat to be equipped with the essentials needed to achieve the level we’ll call Stage 1.

What is Stage 1? It means carrying enough oil and filters to give you a 100 percent back up on the essentials. Most boats that are coastal cruising will start out the season with clean engine oil and a clean filter (you did it in the fall, right?). Therefore, a very minimum level of supplies to reach Stage 1 would be sufficient oil to do at least one complete oil and filter change, plus 50 percent. Why the extra oil — for topping up, of course (you check your oil level frequently, right?).

For those with the storage space, I recommend doubling the basic Stage 1 amounts to avoid having to spend part of your summer vacation in Maine searching for an oil filter. If you are a seasonal sailor you will inevitably end up carrying more oil and filters than you will use in one year, so it is important to label everything with the date purchased. The shelf life of oil and filters is many years, but it does deteriorate somewhat. Life in storage can be prolonged by keeping extra supplies unopened and in a cool place away from light — your basement at home is just about perfect. On the boat it is best to store oil low down near the hull where it is likely to remain relatively cool. Avoid temperature extremes in storage, which means leaving it in the engine area is a no-no.

Also, seal up extra oil filters in zipper-type, heavy duty plastic bags to keep moisture laden boat air from circulating. Filters must be physically protected from damage, so they can’t be stored under heavy objects in the bottom of lockers. The casings are metal on canister-type filters, but they are still prone to denting. Before using any filter, inspect it for physical damage, especially to the gasket area.

Supertanker: Stage 2
Once you leave the more developed parts of the world, all bets are off in terms of finding suitable oil and filters for your boat. This is true even if there are occasional marinas where you are going, or even reliable mailing and freight services. You can’t expect to always find the same brands and specifications that you are used to. This is when it is time to upgrade to Stage 2 storage levels.

Stage 2 will assume that your proposed route will eventually coincide with a city in a country that offers a modern level of consumer marine goods, or at least offers reliable air transport from your home country. If your route doesn’t already do so, I recommend trying to reach one of these ports at least once a year. An unwritten rule of cruising is that no matter what you have on board, the part that breaks will be something else — at least a lot of the time!

On my 38-foot Finnsailer motorsailor we have an old Perkins 4.236 engine, that requires eight quarts of diesel oil per change. Various sources recommend changing the oil at either 100 or 200 engine hours. In general, I feel that extending the changing time to 200 hours is acceptable when using quality engine oil (usually obtained at home), a quality engine filter, and when running the engine frequently and for longer periods.

It may be counterintuitive to some, but very short runs of the engine under no load are considered “severe service,” while running the engine continuously at operating temperature for many hours is considered to be much easier on your oil and your entire engine. Most engine wear occurs at start up, when your oil is cold and has drained back down out of much of the engine. Fresh fuel injected into the cylinders washes off what little oil is there, and possibly some of the fuel leaks by your somewhat worn rings. The sluggish cold oil takes a bit of time to get circulating properly, maybe only seconds, but during this time there may be some metal-to-metal contact within various parts of the engine. In addition, some of the oil additives require sufficient temperature to perform their functions. These are some of the reasons that it is very important to warm up a diesel engine properly before you apply load.

Therefore, those of you who feel you are babying your engine by just using it to break out the anchor before shutting it down may actually be shortening engine life significantly. It is important to run a diesel for long enough for the oil, coolant, and entire engine to get up to full temperature and stay there for at least 20 or 30 minutes in order to boil off any excess fuel contamination and moisture accumulated in the fuel. So, if you use the engine to get the anchor up, it is better to also use it to motor out of the harbor, as much as it pains the avid sailor to do so.

Going back to my boat, the Finnsailer 38, I use the 200-hour change interval because I almost always run the engine for at least an hour at a time, especially when voyaging. If you’re doing something like the Intracoastal Waterway (ICW), with eight or 10 hours of motoring per day, you’re actually taking it easy on the engine, so definitely consider extending your oil-change routines then.

Stage 2 requires at least a doubling of your usual stores of oil and filters. On my boat that means a total of 24 quarts of oil (six gallons) and two filters. I usually cruise at six knots, but allowing for engine running for electricity generation and a safety factor, I figure this much oil lets me safely go 400 hours at five knots or 2,000 miles of motoring. Looked at another way, I can run the engine one hour per day every day for more than a year. I think that is a good rule of thumb for most voyaging boats.

I hear the screams from the sailing purists out there, but the reality for many cruisers is that the main engine is a major source of electricity generation and/or refrigeration power, so I think an hour a day for a full-time, liveaboard voyager is actually a pretty modest expectation. If you have a power trawler or you expect to do long stretches under power (ICW, European canals, the doldrums) you may find that having enough oil for 400 hours is not enough.

Where’s Waldo’s oil?
You’ve now planned your trip so that you can end up in a good resupply port at least once a year, and that year is up. Your oil and filter supply is low. Now what? In many parts of the world where cruisers voyage you will experience some culture shock when you begin looking for supplies and parts, and your oil and filter needs will be no different. Of course, diesel engines are used all over the world, and many marine engines are basically repurposed industrial engines, so theoretically supplies should be readily available. The problem is that the particular products you are accustomed to may not be available, and it is often very expensive to have these heavy and bulky items shipped in.

Chances are you will be searching the dusty back alleys of some large town or city looking for a suitable name-brand oil that will work. You may be lucky and find exactly what you want, but it is just as likely that you will have to substitute. Following are some general suggestions as to what to look for, but you should research carefully your own engine’s particular needs before leaving civilization.

First, steer clear of oil brands that you have never heard of. This is possible in most countries. Companies like Shell, Texaco, Mobil, and Chevron all have well-known U.S. and European diesel oils, while at the same time offering similar products around the globe. Shell products seem particularly widespread in areas that I have traveled, though you will probably be looking at jugs of Shell Rimula, not Rotella.

Second, make a copy of your exact oil and filter requirements, and keep a cheat sheet handy at all times. You never know when you might pull up to a fish dock somewhere and discover they have just received a shipment of new oil — it is worth it to be prepared.

Third, you may have to adjust your preferred specifications. For example, in some very hot parts of the world it may not be easy to find multigrade oils, like 15W-40, which is probably the most common diesel oil specification used in the U.S. The 15 part of the multigrade is a “winter” number, meaning that the engine oil flows like a 15-weight oil at cold temperatures. The 40 part means that once the engine oil heats to full temperature it behaves like a 40-weight oil. This effect is achieved through the use of viscosity improvers (VI), which are beyond the scope of this article. However, you can see by this short explanation that if the temperature never gets below say 80 degrees and the water is a similar temperature, your engine will not need an oil that can flow well at say 40 or 50 degrees, as many of us do who sail in New England.

There is nothing wrong with single weight oils, like SAE 30 or 40. In fact, they tend to be very robust and not as prone to shearing (losing their viscosity with age and use) as multiweight oils. You should not hesitate to purchase straight 40-weight oil in a place like Panama, where you know your engine will not be having cold start issues. Many engine manuals have suggested oil weights for various temperatures, and you can use this to your advantage when shopping. In general, if your manual recommends the typical 15W-40 oil, you could safely go to a straight 40 in a hot climate, but stay away from a straight 30. If I had to make a choice between a no-name oil in the proper weight and a name-brand oil in the wrong weight, I probably would go with the name brand (as long as the weight was reasonably close) and just take it easy on the engine until I could find the correct oil to make a change.

Another problem can arise with the American Petroleum Institute (API) rating of the oil. The current API Service Classification is CJ-4, which you should be able to find printed on most oil containers sold in the U.S. The previous classifications were CI-4 Plus, CI-4, CH-4, and CG-4, so you can see they have been progressing alphabetically. Chances are slim you will find anything on the market in the U.S. that doesn’t have at least the CI-4 rating. The classifications are backwards compatible, meaning that you can safely use the latest classification in older engines. If you have an engine that was built in 2007 or later, it may specify the CJ-4 classification, and you should be wary of using any of the older classifications. The current CJ-4 standard was developed to work with modern engines using diesel particulate filters (DPF) and in some cases exhaust gas recirculation (EGR) using ultra-low sulfur diesel fuel. If you have one of these engines, chances are you will need CJ-4.

In addition to the API classification, some diesel engine companies have created their own standards, which you will often see printed on the back of major oils. Some examples of these include: Caterpillar ECF-3, Cummins CES 20081, and Volvo VDS-4. There is a whole slew of engine specific standards, and if your engine company requires one of them to maintain warranty you should put that information on your cheat sheet. But, as outlined above, don’t expect to always find one of these oils when you’re scrounging around in some third-world port.

Older engines will be fine on CI-4 Plus or CI-4 oil, and some believe that the higher levels of some additives in the older oils helps to reduce wear. However, every oil manufacturer claims that their latest CJ-4 oil is great for older engines.

Not all natural
One possibility for extending your oil drains even further is to use a synthetic motor oil, like Shell’s Rotella T6 5W-40, readily available in the U.S. at any Walmart or truck stop. Some say you can double your normal drain interval. Many trucking fleets and consumer diesel truck users have switched to synthetic oils for their superior wear protection, improved cold starting flow, high-temperature tolerance, and long drain capability. However, the marine world has been slower to adopt synthetics, some manufacturers may not allow them during the warranty period.

One danger seems to be that switching from regular oil to synthetic in older engines may create oil leaks. Synthetic oils tend to clean engine deposits, and some of those deposits may be blocking minor oil leaks. It will probably be much more difficult to find appropriate synthetic oil outside of your home waters.

Don’t forget the filter
There are many more different types of oil filters than there are different oils, so finding your specific one may be difficult at times. Taking up less space than jugs of oil, it is possible and wise to carry more filters than required for the number of oil changes you have on board.  

Most oil filters utilize a very similar construction, and it is relatively easy to cross-reference your specific filter to more generic items that may be more widely available. The key dimensions that need to match are the gasket diameter and the thread diameter and pitch. Less important, but still desirable is to find something with similar outside dimensions to your filters in order to get an equivalent amount of filtering area and dirt-holding capacity.

For example, the Perkins filter 2654403 specified for my engine matches up perfectly with the widely available Motorcraft FL-1A dimensions, and these can be purchased at any auto parts store for less than $4 each. There are numerous other brands of filter on the market that match up with this size, and I keep a list of many alternatives on my cheat sheet along with the oil specifications. It is also useful to find a common road vehicle that uses the same size filter and make a note of it — some auto parts places like to look up parts by vehicle. For example, my filters would also fit the very popular Ford F-150 from the mid 1980s.

Make sure your replacement filters have bypass valves if your OEM filters do, and the pressure settings of the valves should be similar. The bypass allows oil to flow to the engine when it is too thick due to cold, or when the filter is clogged. In these conditions it is more important to allow the engine to receive somewhat dirty oil than it is to filter out every particle. Apparently, there is some leeway on pressure settings because various brands specified for the same engine sometimes have slightly different specifications. Some engines have unusual requirements in this regard. Also, be very careful not to put on a filter with no bypass if one is specified. Some engines have the bypass built into the engine and do not require one in the filter.

Most major filter brands found in auto parts stores, like Fram, Purolator, and Bosch have various grades available, and as a rule the more expensive grades tend to have stronger construction, better filter media and more of it, greater dirt holding capacity, and frequently silicone rubber anti-drainback valves (ADBV), which remain more pliable under both cold and hot temperatures than the more common nitrile valves. I have contacted filter manufacturers and they say that there is no reason standard consumer grade filters can’t be used on diesel engines.
The best source for all of this cross-reference information is readily available on the Web at, and be sure to write down what you find on your cheat sheet.

John J. Kettlewell is a marine author and editor based in Saratoga Springs, N.Y.

By Ocean Navigator