Used oil to power our diesel boats

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
RickyD said:
I have never been over there except to get fuel at Jankovich. What is Al Larson's good for?
Click to expand...
It is a large boat yard for the big boys. They've been in operation for over 100 years.
The used oil vat looks like it can hold at least 1000 gallons or more.
 
Al Larsen Marina, brings back a lot of memories from when I spent time at the CG station on TI.
 
I might try this. A drain is 8 gallons from the 2 engines and pouring into the 2 most filled tanks (over 100 gallons each at half full, got 4 tanks) would be less than 4% and save me the trip to the recycle dump.

I pump the oil out, so not much sludge me thinks and it can only help lube the injector pumps. Engines are 1979 Volvo TAMD 60B. Pouring into the top of a 3/4 full tank should be good for dispersion.

I think I'll do this next oil change and save me lugging 8 gallons of oil across the dock, down the gang plank, into the car and out the car into the shop. Just dump it down the deck fills - :)
 
Your boat may smoke some due the oil addition but thank God you’re not in CA where the smoke police will get excited.
 
I am in California.

Stockton, CA. Heart of the Delta.
 
when i see the results from oil test seems like a lot of stuff in the oil.
 
Dirty, but probably OK.

pete
 
I dumped the waste oil from my two 120 Lehmans and the Onan generator back into the fuel tanks on my GB which had two 190-gallon and two 130-gallon tanks. I usually changed oil in both main engines at the same time and put the oil in whichever tank was the fullest on that side of the boat. I never ran fuel in them from the opposite side of the boat. It was easier to do this than to lug the oil to wherever to get rid of it. Never had any problems in 29 years.

Fast forward to my current high-rpm Yanmar and, NO SIR, I won't do it, especially since the new Floscan I installed specifically recommends against the practice of running used oil because it will screw up the optical sensor.
 
You would get more reliable advice from your engine manufacturer than you will on a web forum, but my "advice" would be to forget about it. You won't save enough money and you will risk damaging your engine, especially if it is a newer model.

If fuel costs are a big concern for you, you might try cruising at a slower speed and emptying unneeded "junk" from your boat to lighten it.
 
Think many who do it or are considering doing it...the reason is ease of disposal rather than economy.

Most of my oil drains involved oil that really didn't look bad and never had much or any sludge...if it did, it was still in the bottom of the container when I poured it someplace else.

Most likely with older Perkins and Lehmans...with low micron primary and secondary filters and pre filtered fuel oil bought at most continental US fuel docks...I seriously doubt those engines would be hurt by the dilutions of one oil change per tank (100 gal or so with 2-3 gallons waste oil) would cause. New, expensive, high tolerance engines....no...probably not.

If you can dispose of used oil easily...then I agree why bother. But if not and you don't have the room to lug it around and not a worry wort.... I would love to see the tech data on how it is hurting these old engines.

Sure manufacturers won't recommend it...but after 50 plus years of service...there is a lot that the manuals don't cover.
 
Some of the concern could also be reduced by finding a way to pre-filter the used oil before feeding it into the tanks.
 
psneeld said:
Think many who do it or are considering doing it...the reason is ease of disposal rather than economy.

Most of my oil drains involved oil that really didn't look bad and never had much or any sludge...if it did, it was still in the bottom of the container when I poured it someplace else.

Most likely with older Perkins and Lehmans...with low micron primary and secondary filters and pre filtered fuel oil bought at most continental US fuel docks...I seriously doubt those engines would be hurt by the dilutions of one oil change per tank (100 gal or so with 2-3 gallons waste oil) would cause. New, expensive, high tolerance engines....no...probably not.

If you can dispose of used oil easily...then I agree why bother. But if not and you don't have the room to lug it around and not a worry wort.... I would love to see the tech data on how it is hurting these old engines.

Sure manufacturers won't recommend it...but after 50 plus years of service...there is a lot that the manuals don't cover.
Click to expand...
This sums it up nicely.
 
Used oil in fuel tank

Good morning all. My career was 35 years in the marine fuels and transportation industry. Putting used oil in fuel tanks of ultra lo sulfur diesel is absolutely the worst thing you could do. Short term may work but eventually injectors will take the big hit from carbon and other additives in the lube oil that no amount of filtering will remove. If it’s a warranty issue fuel samples will be taken. Next will be the hi pressure injector pump. Repair cost will far outweigh any fuel savings. Engine failure at a critical time
Could endanger crew and vessel.
Recycle used oil responsibly. Not worth the risk.
 
I used to sail tugs and mega yachts that would routinely add waste oil to the fuel. Some boats would directly add to the tanks, others had a system (I believe it was made by Racor) that would add the oil to the fuel as it was used.
The only thing I noticed was the Racor filters would be black when I changed them, the final filters would not have black in them.

Some vessels had a fuel centrifuge, I believe I noticed a bit more muck being extracted but nothing proven.

Oil is oil, you can refine waste oil to diesel.

M
 
I wouldn't! I have an older Lehmann 135 and I still wouldn't do it. It's black, full of soot, and at the very least would add sludge to the bottom of fuel tanks or clog fuel filters. Just send it to recycling and make it someone else's problem.

Edit: at most I would change oil once during a trip. I have a container and take it back to my home marina for disposal.

Edit again: Having read through the posts, I would still say no. It might be fine when it reaches the engine, because of filtration, but the possible sludge at the bottom of the tanks would make me say now. Also the fuel filters would likely need to be changed more frequently.

Jim
 
Last edited:
"what would happen if, after changing my oil, I poured the old oil into my fuel tanks"


Your engine would thank you. I've been doing just that for decades both cars, trucks, boats. Older engines especially can use the extra lubricity in their fuel.
 
Like a bad penny, it's amazing how this subject keeps rearing its head. We go to great lengths to provide engines with clean fuel, then we consider pouring oil that could be laden with carbon, acid and metal (assuming the engine is in good condition, if not it might include glycol and sodium) into our tanks? The sediment in that oil will settle out and accumulate on the tank bottom, and while it may take a while it won't do filters any good. In short, not worth it on any engine.

Many gas stations in the Northeast where I grew up had oil furnaces, into which proprietors poured waste oil. Probably not legal today.
 
They make "magnetic" oil pan drain plugs. I've changed oil on engines that had those and they had a small amount of fine metal shavings stuck to them. That's metal shavings that the oil filters did not remove.

Now imagine that you drain your engine oil and it contains fine metal shavings as well as carbon, etc. that you may not be able to see. I sure don't want to be dumping "liquid sandpaper" into my fuel oil and into my injector pump and injectors. Nope, aint doing that.

Just saying, a little food for thought that the shortened life of engines and components is not worth it yet alone the possibility of an engine failure at a critical time.
 
rslifkin said:
Some of the concern could also be reduced by finding a way to pre-filter the used oil before feeding it into the tanks.
Click to expand...

NAPA sells canisters and fuel filter elements... if I was going to even consider recycling I think I would but a pump and set up an off-line oil polishing system. I think I would also spring for an extra oil analysis and compare used oil to the "polished" used oil.
 
Kona Kai said:
Good morning all. My career was 35 years in the marine fuels and transportation industry. Putting used oil in fuel tanks of ultra lo sulfur diesel is absolutely the worst thing you could do. Short term may work but eventually injectors will take the big hit from carbon and other additives in the lube oil that no amount of filtering will remove. If it’s a warranty issue fuel samples will be taken. Next will be the hi pressure injector pump. Repair cost will far outweigh any fuel savings. Engine failure at a critical time
Could endanger crew and vessel.
Recycle used oil responsibly. Not worth the risk.
Click to expand...

Plus 1 *** Sure the engine will burn it, problem is the anti wear additives will adhere to the piston crown and cylinder head. Ever seen valve carbon deposits on high mileage engines? It cooks on and is difficult to remove.
If you want lubricity for the fuel add 2 stroke outboard oil to the fuel tank.
It's designed to burn completely and no ash residue builds up in the combustion chamber. :dance:
 
What is ironic about this thread is there are as many people actually doing it and not finding any problems and as many people not doing it and claiming what those problems would be.
 
SteveK said:
What is ironic about this thread is there are as many people actually doing it and not finding any problems and as many people not doing it and claiming what those problems would be.
Click to expand...

The saga of internet debates.... as unusual, further investigation is usually needed beyond TF. But it does help many as they now know the possible pros and cons to go from there.

Most people with experience know that some cautions are well worth considering and others not so much.
 
It's illegal to add used oil to highway fuel in some states.

We were audited by the state of North Carolina many years ago; the auditor wanted to make sure we weren't diluting the highway fuel in our service trucks with used motor oil, thereby avoiding some percentage of the fuel tax on highway use.

The same shop gets most of its heat from burning used motor oil. The heater is commercially produced and EPA approved. But it produces a surprising amount of ash and requires regular servicing.

There no way in hell that I'd burn used motor oil in my modern construction equipment. The manufacturers are so picky about fuel quality in the modern engines that they advise no pre-filling of fuel filters to avoid to risk of contaminants.
 
AB
You are correct. My many decades of experience with off road equipment up to 4,000 HP showed that fuel cleanliness and specs were paramount. Warranties, OPEX and maintenance frequencies needed 100% assurance that fuel and oil be of the highest quality not only when new but through the change interval cycles.

For those saying “no problem” to burning used oil one has to avoid saying “I firmly follow my engine’s oil analysis.” Why? Where do oil contaminants come from on an otherwise healthy engine? Yup, the fuel.

For the brave and willing, talk to a modern engine builder or CARB about this. Shades of diesel gate maybe. If nothing else, don’t take your new Cummins powered RAM in for an emissions check if you’ve dumped some used oil into the fuel tank.
 
Last edited:
In my opinion it is a simple analysis of financial risk. I don't save much fuel cost by burning the waste oil. If I can assume a 1:1 energy density ratio diesel to lube oil it's roughly $32 in fuel savings. I save some difficult to quantify cost in disposing of the waste oil. If I had to buy new buckets each time and pay the mileage to the oil dump maybe $40. I estimate the most financial benefit I stand to gain is $72.

But the potential financial risk is too great. Anywhere from a high pressure pump and injectors overhaul to far more serious engine work.

The risk - reward ratio is not in favor of burning the waste oil. I do what I can to ensure my engines have clean fuel. Why take the chance on messing it up?
SteveK said:
What is ironic about this thread is there are as many people actually doing it and not finding any problems and as many people not doing it and claiming what those problems would be.
Click to expand...
 
Again I don't recommend it, however, if you are intent on doing this, it's worth a lab test. Add a sample of used oil to fuel, in the ratio you intend, and send it to a fluid analysis lab for testing to see if it pushes the fuel out of spec or yields any flags. Diesel testing usually costs about $150.

I think results will have a lot to do with the mix ratio.

They still sell shop heaters that burn waste oil, safer use for used MO IMO...

https://www.energylogic.com/waste-oil-heaters/

https://www.interstateenergyinc.com/waste-oil-burners/waste-oil-furnaces
 
I’ve been on here since 07 and posted may things many on here thought were obviously dubious .. to “I think you’re nuts.” This running waste oil in your main engine to me is unthinkable. But I’ve not needed to put much fuel in my 37hp boat. Me thinks may here have boats too big.

Another thing to think about is were your engine will up-chuck on it’s diet of garbage. If very far north on the west coast you may be where another boat may not come by for a week.

Another thought is to run a big dose of used oil in your generator .. and see how it goes.
 
Nomad Willy said:
I’ve been on here since 07 and posted may things many on here thought were obviously dubious .. to “I think you’re nuts.” This running waste oil in your main engine to me is unthinkable. But I’ve not needed to put much fuel in my 37hp boat. Me thinks may here have boats too big.

Another thing to think about is were your engine will up-chuck on it’s diet of garbage. If very far north on the west coast you may be where another boat may not come by for a week.

Another thought is to run a big dose of used oil in your generator .. and see how it goes.
Click to expand...

I am the OP and I carry 650 gallons of diesel so the oil would be well diluted. I'd try your suggestion but my generators draw from my 400 gallon tank, so then I'd be stuck with it. My big genset is rated at 1 gallon per hour under heavy load. My Cat twins get 10/hour at 10 knots. My reason for starting this was to see if it was a viable way to get rid of the oil since they closed our marina recycling center.
 
You must log in or register to reply here.

Similar threads

C
Single wt oil in Northern Lights Generator?
Replies
6
Views
702
Comodave
Comodave
Waterant
Cure for Yanmar diesel engine smoke?
Replies
12
Views
3K
Dougcole
Dougcole
billblack
85' Trawler Rebuild/refit
Replies
29
Views
3K
billblack
billblack
dwpsco
Dragonfly Update #2 With Pictures
Replies
5
Views
2K
dwpsco
dwpsco
C
Kohler 8kw EOZ question on auto shutdown feature.
Replies
2
Views
512
captmig
C

Latest posts

Back
Top Bottom