Slick and Quick Oil Changes

Turn tough into easy peasy with a 12vt Gear Pump

Thirty years ago a good friend of mine showed me the secret to easy and quick oil changes. Having gotten really tired of fighting a manual oil pump for twenty minutes just to do an oil change. I took his advice and installed a 12V oil rated gear pump.
Ever since the whole job — drain, filter change, refill — takes me about ten minutes. 
And I never get my hands dirty 👍😀.

Most yacht diesels have sumps you simply can't drain from the bottom easily. The manual pump supplied with your engine gets the job done, but it's slow, tiring, and frankly put most of us off doing oil changes as often as we should. A reversible 12V gear pump changes everything — and once you've set one up, you'll be thanking yourself every time you need to do an oil change.

How It Works

The gear pump connects to your sump drain point with a short length of oil-rated rubber hose and an inline on/off valve.
Flip the pup switch one way and it sucks the old oil out in seconds.
Flip it the other way and it pumps fresh oil straight in from the container.
No mess, no effort. Click on the diagram below to see it full size.

Setting It Up

If your engine came with a factory hand pump (Beta Marine, Nanni, many Yanmar and Volvo Penta installations do), you already have the hardest part sorted. The sump fitting is already there. Just disconnect the hand pump hose, add an inline on/off valve, extend with more oil-rated hose to the gear pump, and you're done.

No factory hand pump? Remove the drain plug and fit a 90° 3/8" hose barb elbow with a  in bronze or 316 stainless steel. Most yacht diesels use an M16 × 1.5 thread — confirm yours with a thread gauge before buying the fitting.

Hose spec: Use 3/8 ID  nitrile rubber fuel and oil hose, high-temperature. Like this one. Do not use water hose — it will swell and fail with hot oil.

Doing the Oil Change

Run the engine to warm the oil. Shut it down. 

Open the valve from the sump hose to the gear pump and put the outlet hose from the gear pump into an empty container. 

Flip the switch to suck the old oil out of the sump and into the container. 

Keep a careful watch on the level of oil in the empty container and when it is almost full turn off the pump, carefully move the tube to another empty container and then flip the switch to continue. 

Change the oil filter, drop the pump hose into fresh oil, flip the pump start switch the other way, and it sucks the oil out of the new container and fills the sump for you. Check the dipstick, top off if needed — done.

I've been running the same gear pump on my diesel engines for thirty years. It still works perfectly. One of the best modifications I ever made to our yacht.

The Pump

You need a 12V reversible self-priming gear pump with metal gears and oil-rated internals. After thirty years I honestly couldn't tell you what brand mine is — but it keeps going. The best option currently available on Amazon is the SEAFLO 12V unit below, with reversible flow, copper impeller, and a 4-year warranty.

🔧 Ready to make oil changes a pleasure?

SEAFLO 12V Self-Priming Gear Pump

Reversible flow ·  Metal gears · 3.2 GPM · 4-year warranty

You'll also need 10mm ID oil hose - here's 10m of oil hose complete with stainless hose clamps. 

And here's a 316 Stainless steel Oil rated ON/Off Valve - you'll need this to turn off the oil hose to the gear pump during normal operation. You may need an adapter if your existing sump drain hose has a different ID.  

For the full picture on maintaining your yacht diesel — oil, filters, impellers, zincs, and more — see my  complete diesel engine maintenance guide.

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