Diesel Engine Oil Change Frequency?

[CatboatWilly]

Many companies that maintain fleets of diesels, will tell you that the oil content of their vehicles and/or engines, are change according to a given long period schedule. What is not said is; that the oil is removed from the engine, passed through a 2 micron ceramic filter under pressure and then placed back in to the same engine. A new high quality oil filter is also added at this time.
It's the particulate matter in the oil that usually contaminates .
This is one of the reasons that one should use a 'high quality' oil filter rather than the less expensive models.
If you are unsure about the science of filtering oil or oil filters, check it out on You Tube.

[hellosailor]

ken-
as drp said. The only way to KNOW if you should change the oil, is to send out a sample for analysis. Any commercial boatyard, fleet operator, diesel freight company, etc. is already doing this as part of their routine maintenance. Pennzoil and Quaker State and Shell all used to have programs in the US where they'd only charge $2 to their fleet customers, to encourage brand loyalty, when they charged $20 retail.
If the test says that the viscosity is holding up, the additives are holding up, the contaminants are not a problem...then you can let it go. They'll probably tell you right in the report when to re-check it.
But as soon as you say "turbo"...it becomes critical to make sure, one way or another, that your oil is doing the right job. Turbo systems are hell on lubrication, way more demanding than any Ferrari is going to be. Either you do oil sampling, or you replace the oil as per the manufacturer's schedule. Or, you wait to see how long the turbine units last. Hard choice? Roll some dice.(G)

[MarkSF]

There's something that oil testing doesn't tell you : the state of the engine internals. I used to be a fan of extended oil change intervals, but my opinion has changed somewhat.

My Jaguar XJR has 140K miles, and always had 5K oil changes. Two previous owners ignored the 10K interval advice from Jaguar, and did it twice as often. The condition of the internal surfaces is fantastic - shiny metal on the heads under the top covers. I've seen engines with extended intervals, at half that mileage, with thick black crusty buildup on the same surfaces.

My Discovery V8 had a sticky tappet at idle after 75K miles and extended intervals. Fixed it with regular changes (1500 miles) of Rotella T (high detergent, good stuff).

Remember all the trouble that VW had with the 1.8T - failed engines at low miles, usually 60K to 70K. A combination of low oil capacity (4 qts), extended intervals, and US dealerships' tendency to use cheap oil that didn't meet VW specs.

Extended intervals are for one reason, and one only : to save the manufacturer money during the warranty period.

I'm not one of those luddites who change the oil once a month - but for my own cars, out of warranty, I am sticking to 5K or once a year.

[MarkSF]

"For the past three years I have run a synthetic Delo "diesel only" engine oil"

There is no such thing as diesel or gasoline only oils. Look at the bottle. It has an SM or SN API rating. That means it is suitable for S(park) ignition engines.

The "diesel" bit is a marketing decision.

Running Rotella T6 synthetic in my gasoline Jag XJR. Great stuff!

[Kenomac]

Originally Posted by hellosailor

ken-
as drp said. The only way to KNOW if you should change the oil, is to send out a sample for analysis. Any commercial boatyard, fleet operator, diesel freight company, etc. is already doing this as part of their routine maintenance. Pennzoil and Quaker State and Shell all used to have programs in the US where they'd only charge $2 to their fleet customers, to encourage brand loyalty, when they charged $20 retail.
If the test says that the viscosity is holding up, the additives are holding up, the contaminants are not a problem...then you can let it go. They'll probably tell you right in the report when to re-check it.
But as soon as you say "turbo"...it becomes critical to make sure, one way or another, that your oil is doing the right job. Turbo systems are hell on lubrication, way more demanding than any Ferrari is going to be. Either you do oil sampling, or you replace the oil as per the manufacturer's schedule. Or, you wait to see how long the turbine units last. Hard choice? Roll some dice.(G)

Understood. So... since the manufacturers recommend 150hrs on the Yanmar and 100hrs for the Westerbeke, should I wait until next year? At the end of this season, I have only half the recommended hours and the oil quality these days is much better than twenty years ago. Mostly synthetics these days.

Neither manufacturer recommends changing oil according to a time interval, only by hours.

[Pyxis156]

Originally Posted by MarkSF

"For the past three years I have run a synthetic Delo "diesel only" engine oil"

There is no such thing as diesel or gasoline only oils. Look at the bottle. It has an SM or SN API rating. That means it is suitable for S(park) ignition engines.

The "diesel" bit is a marketing decision.

Running Rotella T6 synthetic in my gasoline Jag XJR. Great stuff!

Poor choice of wording on my part... the Delo 400LE Synthetic is indeed CJ-4 and SN rated.

[hellosailor]

About the internals.

Around 1984, when Mobil1 was that freaky new expensive stuff that no one had heard of? My friend worked in the Mobil NYC corporate PR offices. And he passed me a complete "industrial" press kit on Mobil1.

They had the cleverness to run in in a fleet of NYC taxi cabs, typically hot engines in use 24x7 in what every manufacturer calls "extreme service" conditions. And they ran 'em for 50,000 miles and then broke the engines down.

Valve covers, valves, pistons, in the Mobil1 engines? Looked brand new. In the conventional oil engines? Full of black coke and tar deposits. Made a fast and easy decision when you saw the internals. (And it is a HD oil with high amounts of molybdium disulphide dust in it as well.)

Years and years later someone had the sense to do that "glass skillet" tv commercial showing basically the same thing, the way heat didn't break it down.

But generally if you've got oil that is cooking off and leaving black deposits in the engine, the analysis will show similar compounds, in the oil itself. They have to form, before they build up as deposits. And if it isn't breaking down...they aren't forming.

Diesels are of course not gas engines so the performance criteria are different, but the considerations (guess or test, use or abuse) are the same.

[Cadence]

A good oil (Rotella T or alike) and a good filter are so cheap what is the issue. Service cycle is also important. MY wife's car is approaching 4 years old and 7,000 miles it has had three changes. That short duty cycle going a 1 1/2mi. to the store is worse than highway mileage. What have you used your boat engine for? Steaming or docking only?

[Kenomac]

I'd say mostly slow longish motoring, with engine revvs once every hour.

[Three Sisters]

Well, changing it now will lend the benefit of removing much of the contamination contained in the existing brew, as well as the acidic nature. The oil itself is no doubt in great condition however the suspended particles and pH lead one to freshen things up a bit before periods of storage. Highest or high quality filters, too. What are the filter choices, if you will ?

Have fun !

[Deltasailor]

Originally Posted by Mike OReilly

We have very different engines and different cruising grounds Ken, and I know very little about all this black magic, so far be it from me to give you any advice. I can say that I change mine at the end of every season, or when we hit around 100 hrs. But mine is an older Perkins 4108 (40 hp).

I’ve always appreciated the adage that oil is cheap, engines aren’t. Seems like cheap insurance to change the oil every 100 hrs or at the end of the season.

P.S. 100 hp! Holy schmolly. Can you get your boat up on a plane with that engine? I bet you could water ski. Me, jealous .

I had a 4108 in my Endurance 37. It had been a static test diesel in the Perkins factory when I bought it second hand. They said it was rebuilt, possibly with can of spray paint, however that engine sailed to Greece, did 10 years of charter then back to the UK. No problem, but it was a very dirty beast a day or so after changing the oil it looked like you could tar the street with it.
I would change the oil at least at the end of the season.

[Kenomac]

I purchased a bunch of these a while back at a great price.

[charliehows]

there are 2 opposing trains of thought on this - 1. the old approach (which i am locked to by habit) - you cant change the oil too often. 2. the 'new design engine' approach - modern engines are so well made that you can completely ignore them and they'll probably keep running forever.
balanced between these arguments is the knowledge that the risk one is taking is pretty simple ; do i waste $100 on oil i may not need to avoid a $20,000 - $50,000 engine replacement.

[Three Sisters]

Nice. Yanmar branded filter for a Yanmar engine. She should be happy !!

I hope this is an easy-ish task without contorting into uncomfortable positions and sparing you hot oil splashing all over the place. As you mentioned earlier it's not your first time.

[Kenomac]

Our Yanmar engine is 16 years old with only 2,000 hours on it, the Westerbeke generator has only 1,400 hours.

Changing the oil for both engines takes a total of one hour. Mostly clean up.