Synthetic lubricating oil for marine diesels

[Elie]

A friend of mine, changed from mineral to synthetic oil for its 1984 Perkins engine. To his dismay, it created havoc to the oil seals. Engine leaked like badly from front and rear crankshaft seals. Modern engines might be ok with synthetric oil, but for older engines caution is a good idea.
By the way, synthetic oil is usefull for long oil change intervals. But up north where boats are stored for winter, regular oil is more then adequate since you need to replace it each fall anyway.

[buzzstar]

I am old enough to remember when oils with additives and in multi-grades (e.g. 10-30) came on the market, at least the general market. They cost more, and received a lot of negative flack. Examples of the latter ranged from, "they will burn up your engine" (multi-grades), to "they will clean out old crud and the engine will burn oil and/or leak like crazy." I even remember being told not to put the oils in new cars because they would not break-in properly. [I had no new car, I worked in a filling station.] I used them in my well worn 1946 Chevy and they worked fine. I've used synthetics for many, many years in both cars and boats, including diesel engines without any identifiable problems.

All of this is only evidence, only from one source (me), and does not constitute conclusive proof, but it might be lumped into the mix with other replies, and unless someone comes up with actual (not what they have heard) evidence to the contrary, it might be worth considering. BTW, the recommendations of engine manufacturers can be, and often are, are influenced by contributions of product or other valuable consideration from the manufacturer of the accessory product -such as oils. Just watch out for the "what I've heard" type stories that I mention at the start.

[freshalaska]

Good to hear from an old timer.

[ArmyDaveNY]

There was a very interesting comment on a different thread (alas, I don't know which one it was) on the forum from an oil engineer. He stated that it is best to stay with the same oil that has been used if possible. The reason for this is that different oils have different properties and these properties can affect the seals. He did state that rarely will one a difference right away.

The way he described this effect was that when changing brands and types regularly you were more likely to see a negative effect than an occasional change of brands and type.

His discussion was very well laid out and had some very interesting technical details. Sadly, I am doing a poor job of relaying his information. I guess the answer is that a one time change of brands won't hurt much but a constant change of brands and type may have a long term impact.

[buzzstar]

Originally Posted by ArmyDaveNY

There was a very interesting comment on a different thread (alas, I don't know which one it was) on the forum from an oil engineer. He stated that it is best to stay with the same oil that has been used if possible. The reason for this is that different oils have different properties and these properties can affect the seals. He did state that rarely will one a difference right away.

The way he described this effect was that when changing brands and types regularly you were more likely to see a negative effect than an occasional change of brands and type.

His discussion was very well laid out and had some very interesting technical details. Sadly, I am doing a poor job of relaying his information. I guess the answer is that a one time change of brands won't hurt much but a constant change of brands and type may have a long term impact.

I do no recall much detail, but it was (perhaps still is) probably true in a few (very few?) specific situations. Examples might include real rubber seals, although I believe most, if not all, engine seals are now synthetic. I do recall an older Ferrari engine that in which "bear grease" (yeah, grease made from a dead bear) was supposed to be used for the initial lube material when installing new crankshaft bearings. I heard this one directly from a mechanic supposedly reading from the manual, but then I do not read Italian and cannot otherwise verify the correctness of the statement.

[ArmyDaveNY]

Originally Posted by buzzstar

I do recall an older Ferrari engine that in which "bear grease" (yeah, grease made from a dead bear) was supposed to be used for the initial lube material when installing new crankshaft bearings.

Bear grease! That is one I had not heard before. I quick check shows they still sell it! (https://www.amazon.com/bear-grease/s...Abear%20grease)

It has uses such as conditioning leather and use on axles. As early as the early 1600's was also rumoured to cure baldness. It is also apparently good for cooking. Here's an enthusiast's site that shows you how to render bear into bear's grease. https://www.wildedible.com/blog/bear...rendering-lard. Who knew?

[Lepke]

I'm old and have run all kinds of marine engines including steam. While synthetic oil has some advantages, it doesn't really last longer. Just as much soot goes into synthetic oil as any other oil. The point of changing oil is to remove the dirt the oil is carrying. Oil carrying too much soot and other debris will allow buildups in the pan and also the oil passages. Especially small hot passages thru the head. Like the oil supply to the turbo. It also builds on new style injectors that are electrically controlled. Because of their tiny parts and clearances. Fresh oil cleans some of the deposits, but not all.
I've been through this many times with longer oil change cycles promised but never really delivered. Extended oil changes has always led to sludge. The only ways I have found to extend oil life is with a bypass filter or a centrifuge. And I've been experimenting with longer oil life since the 60s.

[Barney21]

I must confess I am a total Synthetic oil convert. I have used it in all my vehicles tractors race cars etc.
The reason is simple ,I have a "Same" tractor with air-cooled Deutz engine, all year it would run at normal temp (lived in semi-tropics) for 3 months of the year it would pull a 5 ton harvester after it had been running for 2 hours the temp gauge would be off the dial, I changed to Mobil 1 Synthetic oil and temp would not go over normal, running 12-14 hours a day. Now if that is not proof there is less friction, I was convinced.
As some poster suggested that he has to drop the oil to change the filter and then putting the oil oil back in the engine -- now I know pennies saved etc but really!

[CalmSeasQuest]

Originally Posted by Lepke

...While synthetic oil has some advantages, it doesn't really last longer. Just as much soot goes into synthetic oil as any other oil. The point of changing oil is to remove the dirt the oil is carrying. Oil carrying too much soot and other debris will allow buildups in the pan and also the oil passages...

For diesels; this...

[Scaramanga F25]

In some older engines as in my old Ford SHO ( Yamaha DOHC engine ) the entire gaskets had to be replaced when we switched to synthetic.

So beware and check specifications from manufacturer.

[Miss Saigon]

My answer is based on my personal experience as a former Marine Engineer (Submarines) that later worked for a fuel and lubricant company for 25 years. When I replaced my Perkin 4.236M engine with the same model, I contacted my former work colleagues in the lube company to get the best advice.

The cost of paying a premium for lubricants is a small part of boating and I wanted to et it right.

The were able to assist in a few ways including brewing a special batch of Perkins 'running in fluid' for me. In terms of ongoing lube oil for the engine they advised using a marine grade 15W/40 mineral oil. They advised against synthetics, not due to performance (these guys are the F1 lube team), but simply to not waste my money (think they don't want me back as their boss again). The marine grade has a sticky additive to assist with oil retention on the cylinder walls etc between runs. Their advice was to replace oil as per manufacturers recommendation (200 hours) or annually. After about 1500 hours the oil is very clean when I replace it ever service. I cheat a bit and change the filter every service as the cost is insignificant and once I am down in the bilge and dirty, I might as well do the lot.

I would consider the effect on oil seals, as some of the older engines are not so tolerate!

Beyond this synthetic oil add a lot of added protection and reduced wear on machinery that is stressed well beyond design or normal operation think F1 or a mine site that works equipment 150% above capacity to meet demand.

My work colleagues would often recommend a synthetic replacement over changing out a reduction gear box etc.

[Barney21]

Originally Posted by Miss Saigon

My answer is based on my personal experience as a former Marine Engineer (Submarines) that later worked for a fuel and lubricant company for 25 years. When I replaced my Perkin 4.236M engine with the same model, I contacted my former work colleagues in the lube company to get the best advice.

The cost of paying a premium for lubricants is a small part of boating and I wanted to et it right.

The were able to assist in a few ways including brewing a special batch of Perkins 'running in fluid' for me. In terms of ongoing lube oil for the engine they advised using a marine grade 15W/40 mineral oil. They advised against synthetics, not due to performance (these guys are the F1 lube team), but simply to not waste my money (think they don't want me back as their boss again). The marine grade has a sticky additive to assist with oil retention on the cylinder walls etc between runs. Their advice was to replace oil as per manufacturers recommendation (200 hours) or annually. After about 1500 hours the oil is very clean when I replace it ever service. I cheat a bit and change the filter every service as the cost is insignificant and once I am down in the bilge and dirty, I might as well do the lot.

I would consider the effect on oil seals, as some of the older engines are not so tolerate!

Beyond this synthetic oil add a lot of added protection and reduced wear on machinery that is stressed well beyond design or normal operation think F1 or a mine site that works equipment 150% above capacity to meet demand.

My work colleagues would often recommend a synthetic replacement over changing out a reduction gear box etc.

F1 is not relevant as they are never started cold,they run 12-15000RPM+ as opposed to a usual marine diesel 3500rpm on a good day.
A F1 engine is heated to operating temperature by running hot coolant and hot oil through the engine before startup.The Crankshaft to bearing clearance is 10microns. Oil seals etc may not be compatable with some old engine, Rope rear main seals went out 50+ years ago. Honda F1 engines all ran roller cranks, most F1 engines run oil feed from the front of the crankshaft is does not come down through the block and they run dry sumps. Just my 6 pence worth!

[ballvalve]

everything i have read in the past states that changing to synthetic can cause issues whilst sticking with what you have won't, so why bother? I have also heard that the cleaning properties of some synthetics are so good they can remove sludge which can then go around the engine before getting to the filter and block an oilway, well if that is remotely possible I wont be changing.

[stnick]

I just changed my oil yesterday Ted Brewer Morgan 38 Perkins 4 108 1982
I used Shell Rotellia 15/40 . new filter new oil .
I would change after 3/4 of you guys would change with no trouble. ! Im shy about my engine. she likes what she likes. Tarpon springs fl