When you move up in boat size from a single- to a twin-engine boat, everything in the engine room doubles. Now you've got two fuel filters, two serpentine belts, two water pumps, two fuel tanks and two oil systems, among other things. My last boat - a Sea Ray 260 Sundancer - had a single 320-hp, 6.2L MerCruiser MX, and because my kids were young, I'd consider myself lucky to get 50 to 60 hours on the boat in one season here in the Northeastern part of the country. But now that the kids are a little older, we're able to cruise longer and farther, which means I'm putting more hours on the engines in a regular boating season.
After the break-in period of 20 hours on new engines, which requires an initial oil change, MerCruiser recommends you change the oil every 100 hours and use protective FCW-rated oil, specifically formulated for marine 4-stokes and recommended by the NMMA. (For Northern boaters, regardless of hours, the oil should be changed at the end of the season.) After putting 50-plus hours on my new boat - a Sea Ray 320 Sundancer - over a six-week period, I realized that the price for an oil change had doubled at my dealership. Now it would cost about $150 - not including oil and filters - plus, it requires me to bring my boat to the dealer by water, leave it, have them haul it, and then return to pick it up. What a hassle. So, if you're changing the oil two, or maybe even three times this season, you might consider doing it yourself. But read on and decide if the pain of changing your own oil has benefits worth the investment.
The first thing you have
to do when tackling this project is to buy something to pull the old "Texas tea" out of the
dipstick. Check the owner's manual to be sure about the oil capacity of each engine. For most
twin-engine applications, a standard 3-gallon bucket with an electric pump will do the job nicely
and quickly. If you're on a budget, you can buy a hand pump and manually pump the oil into a
5-gallon bucket. A special-ordered, 5-gallon Jabsco pump/bucket will do a great job, but will cost
you $200. Hopefully, that cost can be amortized over the many oil changes you'll perform in the
next few years.
Next, you'll have to make sure that the tubing that comes with the pump will fit over your dipstick, or if it comes with a screw-on fitting, that the fitting will mate in an airtight manner with the fitting on your dipstick. In addition, you'll have to buy rubber gloves, an adjustable filter wrench, two new filters and a few gallons of new oil. The total can come to $300, so $150 from the dealer will start to sound pretty good - but it's too late for that; now you're committed.
Sometimes powerboats involve hooking up fuel-flow gear to the engines. The job of clamping a
little hose onto a dipstick is fairly easy; the tricky part is setting up all this gear in perfect
position so you can get to everything you need right when you need it, even with your legs sprawled
all over the engine. That part will take a little forethought on your part.
The first step is to warm up
the engines to heat the oil. Anything over 140 degrees on the oil temperature is fine, so you can
run the engines for five minutes, get the oil temperature over 140, and shut 'em down. Next, you'll
move the electric pump/bucket into the engine room, connect it to the battery, slide the plastic
tubing down over the dipstick, and secure it with a hose clamp. The trick here is to make sure that
connection is airtight, so when the pump is running, you don't hear any air gurgling at the
connection. Assuming you have an airtight connection, it should only take about two minutes to suck
the oil out of one engine using an electric pump.
Changing the filters is just about as easy, and with a little paint bucket underneath them to catch excess oil (very little should come out of the old filter), you should be able to do the job without spilling a drop. Just be sure to put a coating of fresh oil around the O-ring seal on the new filters before screwing them on.
Finally, you're ready to refill the system with new oil, and at that point, you must double-check the manual to make sure you know exactly how much oil each engine holds. When you're ready, you'll get out the big funnel, add the oil to each engine, check the level on the dipstick, and then fire them up to check for leaks. If everything looks good, shut the engines down and check the oil level again. You'll notice a slight drop in the level since some of the oil is now in the filter.
The last step is to pump the used oil out of the bucket and into your dealer's "used oil"
tank, run soapy water through the electric pump, drain that in the waste oil tank, and then you're
done. But wait! What about the big question of whether the pain of doing this is worth the gain?
Well, the answer depends on several factors:
1. How many times you'll have to change your oil in one season.
2. How handy and athletic you are (since you'll be slipping around in the engine room like a seal on ice).
3. How much time you have to do this (it takes about two hours start to finish).
If you're doing less
than 100 hours a year on a single engine, you should probably choose the $150 at the end of the
season and let the dealer do it. If you're an avid boater doing 100 hours or more, have twin
engines and you're handy, you may be able to save some money in the long run by doing it yourself.
But just remember, once you go down to your local marine supply store and plunk down $150 or $200
for one of these power oil-changing systems, you're committed to the finish.
Quick Tips
- Change your oil every 100 hours and use FCW-rated oil.
- Check the owner's manual to determine the oil capacity of the engine.
- Make sure the tubing from the pump has an airtight fit over the dipstick.
- Warm up the engine for a few minutes in order to heat the oil.
- Apply a fresh coat of oil around the O-ring before sealing a new filter.
- Check the dipstick/oil level for a second time after you check for leaks.