Diesel Engine Oil

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BonesD

BonesD

Senior Member
Joined
Apr 23, 2019
Messages
268
Location
USA
Vessel Name
Michelle
Vessel Make
1977 Schucker 436
Changed the oil In my PerkinsMarine 4-236 and after about 39 hours of running the oil still looks almost new. This engine has over 7000 hours on it.
My old Massey tractor with a Perkins 4-108 was dirty as soon as I replaced it. Besides my marine generator which has very clean looking oil as well these are my only experiences with diesels. Is this a regular thing with marine engines. I can only guess it has something to do with the raw water cooling system a land machine doesn’t have.
Thanks
 
no....some engines blacken oil fast....and its how much oil gets left behind in pan, coolers, lines, etc.

Its also a little bit of the type of oil I gave heard.

Same with land vehicles...it varies widely.
 
BonesD said:
Changed the oil In my PerkinsMarine 4-236 and after about 39 hours of running the oil still looks almost new.
Click to expand...

Did you do an oil change after just 39 hours? How are you checking the oil color?

Incidentally, oil doesn't typically circulate through the dipstick tube. If you're judging oil color by checking the oil level via dipstick, this may be misleading.
 
When you change oil about 10% of it remains in the engine. Perhaps even 20%. This dirty oil mixes w the new. I think most of what appears to be black is carbon.

You could easily do an experiment and combine 15% dirty oil w new oil and see if it looks the same.
Dosn’t much matter to me as I often change oil in cars w/o changing the filter. On my boat the filter is small so I change it regularly. What’s important is that you have plenty of new oil coming in frequently.
 
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No, I didn’t change the oil after only 39 hours but just did some cruising on a fresh oil change and I checked the oil level prior to pulling the anchor each time we moved. I was amazed at how clean it was staying. M guessing by the responses this is not common. I’m not worried about it as the engine runs like a sewing machine, just curious. This was my first outing since purchasing last November so my history with the engine is minimal. Thanks for the responses!
 
Oil in my 4.236 stays pretty clear through 100 hours. I had a 4.108 and it was only so-so. Years ago I had a Peugeot 504 diesel that was black-black-black the moment the oil was changed. I remember accusing a Jiffy Lube oil change place of not changing the oil and they changed it again while I watched. Still black.

Since then, I've changed a lot of engine oil in Diesels as many boats I delivered were new and the OEM specified the break in oil be swapped out at 100 hrs. All that I can remember were fairly translucent at 100 hours similar to my 4.236

Behold the mystery of Diesels.

Peter
 
My FL 120 oil looks clean 10 to 20 hours after an oil change. I don't leave too much oil in the pan after sucking it out of the pans bottom. The drain fitting is on the starboard side of the engine and I induce a slight heel by moving weight to the starboard side before sucking out the oil.
 
Every day something new!
Thanks all
 
I usually run 8-12 hours after startup, the soot is mostly accumulated on startup. So the more running you do at temperature and the less short hours you run, the cleaner your oil looks. Also agree looking at your dipstick isn't a gauge of oil quality, since it's a very thin sample of your oil.

Good comments in this thread!
 
Why wouldn't oil circulate into the dipstick tube?
 
There’s a certain amount of “splashing” that takes place inside the crankcase. Perhaps you’ve heard of the splash system of luberication that gets the job done in many of the cars in/from the 30’s and lawnmower engines.
In our diesel inboard engines all the oil that gets pumped to bearings goes high in the engine and flows/drips back down into the crankcase to repeat the cycle.
The air being swirled by the crankshaft and slammed back and forth by the pistons moves a lot of the falling oil all over the place. Some will find it’s way into the dip-stick hole. I’ll bet if you put your finger over the dip stick hole you’ll feel a fluttering and if you remove the dip-stick and rev the engine up oil will be spit out the top of the tube. With a very old engine you may get bathed w oil ... hot oil so don’t try it.
That’s my take on oil in the dipstick tube.
 
Much depends on the engines filtration.


ON most full flow setups the oil gets black rapidly , with bypass filtration colorusually takes far longer.
 
AKDoug said:
It's static!
Click to expand...


Every time you start the engine a large amount of oil gets pumped out of the sump and to the top of the engine. Any oil in the dipstick drops and gets mixed with all the rest of the oil until you stop the engine and wait the 15 minutes or so for most to travel back to the sump.
 
Nomad Willy said:
.....if you remove the dip-stick and rev the engine up oil will be spit out the top of the tube. .
Click to expand...
That actually happened to us while cruising Desolution Sound years ago. After stopping for the night, the owner checked the oil level and left the dip stick out by mistake. An ER check later the next day found oil all over the drip pan and on the ER Floor. Now, I believe that oil does circulate in the dip stick tube as well.
 
I don’t know how long ago crank shafts were meant to splash around in the oil sump, maybe with very slow rpm engines they still do The crank should not be dipping into the oil as this can cause foaming and create cavitation in the oil pump so instead of nice pure oil you end up pumping a bubbly air/oil mixture to your bearings. Big reason to never overfill your oil sump. The dip stick is for measuring the oil levels and it certainly is a good indicator of the oil that is in the sump, you can feel it with your fingers and give it a whiff from time to time.
I check mine frequently, it might save me some money or possibly avert a disaster.
 
that is why oil analysis were invented. Visual inspection don't mean sh!t...
 
On my old venerable engine, oil was getting blackened almost immediately after first use. When I got my water in oil problem I did multiple oil changes in a row to clean the mess. Since my last oil change oil is staying far cleaner, and after something like 30h oil still clean. So this makes me think that, in my case, it was because a good quantity of old dirty oil was remaining trapped.
Now I am considering doing some periodic oil "washing" with 2 or 3 changes in a row to remove excess of sout.

L
 
smitty477 said:
Every time you start the engine a large amount of oil gets pumped out of the sump and to the top of the engine. Any oil in the dipstick drops and gets mixed with all the rest of the oil until you stop the engine and wait the 15 minutes or so for most to travel back to the sump.
Click to expand...

I was basing my opinion on the dipstick on a 350 V8 gas engine, where the dipstick tube runs al the way down into the bottom half of the oil pan. The point where the dipstick is marked for oil level is up inside the tube, not down in the pan where it sloshes around and is recirculated.

I can see no reason why the oil in the tube would be refreshed by the engine being run, as it doesn't circulate down the tube. JMO

Your point may very well be accurate!
 
Along with my slip neighbour, both of us used "Flushing Oil Concentrate" (FOC) in our older marine engines (my Perkins T6-354, his FL 120), according to instructions, followed by CEM's "FTC Decarboniser". Both of us experienced quieter, smoother running as the oil flush concentrate removes hard carbon deposits, particularly on top oil rings. Less smoke overall, oil remains cleaner longer. Good products.
 
I would check to see if you have a by pass oil filter. My oil stays clean 200 hours and i test it 1 time a year for back up info.
4.236 is a dam good engine. One of the best in my book.
Don
 
I’d be very cautious about adding extra additives intended to ‘clean’ the internals. Oils like DELO 400 or Rotella T have very complex performance additive systems that cost millions to develop and approve. Just for scale the current DELO cost something like $20MM in approval engine testing. The additive supplier, which in that case is Chevron Oronite, spends hundreds of millions on R&D. Believe me if some additive miraculously removed ring carbon and didn’t do harm elsewhere it would be used by the majors. Adding anything to modern oils will destroy the chemical balance that ensures that ensures engine longevity. How do I know? 36 years in lubricant and fuel technology for one of the major suppliers.
 
The diesels with which I have had oil change experience over the years always turned the oil black almost as soon as I restarted the engine, which I just thought was normal for all diesels. At least it made it easy to see the level on the stick. When we acquired our current boat with it's Perkins 6.354, I was amazed how the oil stays relatively clear throughout it's life of about 100 hours between changes. Granted, we don't run it hard and usually stay under a boosted rpm of 1650 & I suppose it's also due to the placement of the cooler and filter lines. Maybe everything drains into the pan at every shut down plus there's a plug at the back of the engine just over the oil pan that allows me to stick the vacuum tube all the way into the bottom lowest corner of the pan to get every ounce of oil out.
The only word of caution I can offer is my personal experience with synthetic oil. I read where some would say don't use it in older engines because it will weep past seals and gaskets where conventional oil wouldn't. When we got the boat, it had relatively low hours for a diesel- around 2500- and the bilge stayed as clean as a penny. Well guess what? A couple of seasons ago I was all set to do a fluid change and all the local store had was a synthetic blend. I gave it a go and all was normal until the next season when, after the seasons first longer cruise, oil appeared in the bilge. Lot's of oil! Thanks to Jay Leonard's post about the forward engine mount bolts being drilled into the oil passageway, I healed up most of the source. I still see oil weeping where we never had leaks in the past like a little at the head gasket, an access plate on the side of the block, and similar inconsequential but annoying places.
Coincidence? Perhaps. It is a 40+ YO engine. I can assure you that I'll drive to the next town to find conventional oil from now on, if I have to!
 
Perkins manual said not to use synthetic oil
Don
 
boomerang said:
The diesels with which I have had oil change experience over the years always turned the oil black almost as soon as I restarted the engine, which I just thought was normal for all diesels. At least it made it easy to see the level on the stick. When we acquired our current boat with it's Perkins 6.354, I was amazed how the oil stays relatively clear throughout it's life of about 100 hours between changes. Granted, we don't run it hard and usually stay under a boosted rpm of 1650 & I suppose it's also due to the placement of the cooler and filter lines. Maybe everything drains into the pan at every shut down plus there's a plug at the back of the engine just over the oil pan that allows me to stick the vacuum tube all the way into the bottom lowest corner of the pan to get every ounce of oil out.
The only word of caution I can offer is my personal experience with synthetic oil. I read where some would say don't use it in older engines because it will weep past seals and gaskets where conventional oil wouldn't. When we got the boat, it had relatively low hours for a diesel- around 2500- and the bilge stayed as clean as a penny. Well guess what? A couple of seasons ago I was all set to do a fluid change and all the local store had was a synthetic blend. I gave it a go and all was normal until the next season when, after the seasons first longer cruise, oil appeared in the bilge. Lot's of oil! Thanks to Jay Leonard's post about the forward engine mount bolts being drilled into the oil passageway, I healed up most of the source. I still see oil weeping where we never had leaks in the past like a little at the head gasket, an access plate on the side of the block, and similar inconsequential but annoying places.
Coincidence? Perhaps. It is a 40+ YO engine. I can assure you that I'll drive to the next town to find conventional oil from now on, if I have to!
Click to expand...

I had the same thing happen, not with synthetic but detergent multi viscosity oil, when we bought a 81 Mainship in the 80's. It had a Perkins T6.354.4 with about 400 hours and no oil leaks. The previous owner used Delo 100 30 weight. I could not find any locally so put Delo 400 15-40 in. I thought it's Delo oil how different can they be?

Half a year later while cruising, oil started weeping out of various gaskets and seal. Talked to Jim Danielson, the marine engine guru at Pacific Detroit Diesel in Seattle. PDD was the Perkins Distributor at the time.

First question Jim asked, "Did you change the type of oil?". He told me that older engines had gaskets and seals that shrunk with additives in the oil. He suggested changing the oil back to Delo 100, which I did immediately.

It took two years for the leaks to subside, but not completely. After about 5 years the leaks were almost gone.
 
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syjos said:
Why wouldn't oil circulate into the dipstick tube?
Click to expand...

My experience is it does not have to. The tube ends at the block. The dipstick continues down into the oil pan uncovered. Once again, my experience.
 
"After stopping for the night, the owner checked the oil level and left the dip stick out by mistake. An ER check later the next day found oil all over the drip pan and on the ER Floor."

Sounds like the engine had big blowby and the oil was simply pushed out the dip stick tube.

All of the newest most modern oils that are formulated for more modern engines will function in older simple engines, BUT there is no need for the additive package .

As some have found out the single weight CD oil used when the engine was built seems best.

Old DD two stroke folks MUST use CF2 for their engines.
 
Slo-Mo, thank you for your comment on oil makers’ technology, diligence. Fleet operators study oil performance, fuel, additives, etc., and that keeps oil producers competing hard to produce better products - and we all benefit.

So, with your industry expertise, do you use and recommend synthetic engine oil in marine diesels? If so, do you use the same viscosity as with mineral oils? Is their a brand that you prefer? (My choice is synthetic @15W40, either Mobil 1 or Shell Rotella T6.). I expect less carbon over time and imperceptible wear advantage as major oil companies advertise that less wear and friction with synthetics.
 
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