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Oil!

13K views 44 replies 21 participants last post by  T37SOLARE 
#1 ·
what is the really the right kind of oil for diesel engines?
15 w 40?
20 w 50
plain SAE 50 or 40?

What prompts me to ask this is yesterday's oil change project on my universal 5416. I waited for a nice cool overcast day... no sooner got the project started.. the sun came out! temp shot up to a close 90, in the boat easily 110! ARRRG! But, I stuck with and got it done. The jug of rotella I've been saving for this event is/was 15W40. Everything seems OK, oil pressure, sound, etc. I've always thought 20 w 50 was a better choice.
Please let me know if I'm not ok. WAIT! don't answer that! :D err.. I mean the oil :rolleyes:
 
#2 · (Edited)
Hi there,
My perkins 4-236 owner manual asks for SAE 40 (Delo is one brand that I have heard is good to use). This seems to be a standard oil. Going to a standard automotive supply the 10-40w is way more common and won't wreck the motor immediately if that is all you can find.

Other engines have different requirements.

from your owners manual:
Use SAE 30 HD (CD) or 10W40 heavy duty diesel lubricating oil
http://monmouth.seasmember.com/KeelboatOday/Universal_Manual_2.pdf
 
#3 ·
Diesel motors require an oil that can withstand the soot and other particulates that end up in the motor oil. As far as whether to use multi-grade or a straight grade motor oil, I was of the opinion that straight weight motor oil was the best. I have since changed my opinion on that. Back in the 80's, I rebuilt motors in highway trucks. Cummins and Detroits were our bread and butter. Cummins was specific about using a multigrade oil in their motors. We had a customer come in after one of our rebuilds complaining about his oil consumption. He was using 30 wt oil instead of 10-40. We switched him over to the Cummins recommended 10-40 (or whatever it was) and the owners oil consumption went back down to normal. I was impressed. There is a difference and there is a reason why engine manufactures recommend certain oils.

Oh, and Delo-400 is one of the quality oils for diesel motors.
 
#4 ·
I've been using Delo 100 40W in our older Pathfinder. Our manual says to change the oil and filter every 100 engine ours, but on a sailboat that could take a long time in getting a 100 hours on an engine. Acids build up when oil sits in a diesel for to long (not good for the engine), so I change out the oil and filter every 3 months wheather I hit 100 hours or not.
 
#5 ·
Denise,

As you may know, the numbers refer to viscosity, "thickness" of the fluid. Multi range oils have become the de facto standard. A 15-30 oil supposedly has the ability to hold its viscosity through a range of temperature.

If you use your boat summer only, as most of us do. And you live on the hot steamy side of the continent, an SAE 40 would not be a bad choice. Though if you encounter a 30-degree F. day in August, the viscosity of your engine oil will make it tougher for your starter motor to turn the engine over.

Once started, the higher viscosity oil carries off heat more efficiently than the thinner oil. Any of the weights you listed will work. You will find that oil is like anchors in so much as everyone has a (usually emotional) strong opinion, seldom backed by anything more than anecdote.

Wayne
 
#6 ·
Your engine manual should specify an oil type and weight, and the standards required of the oil. Diesels take a special HD formulation, the container should specify for diesel use. Heres what Westerbeke says:
"Use a well-known brand and try to use the same brand each time you change the oil. Avoid mixing brands of oil. Different manufacturers use different additives, and mixing brands may cause a problem if additives are not compatible. More important is to use the correct A.P.I. (American Petroleum Institute) and S.A.E. (Society of Automotive Engineers) ratings. For Westerbeke and Universal DIESEL models use A.P.I. code CF or CG-4, S.A.E. #30, 15W-40, 10W-30 or 5W-40."
 
#7 ·
Changing oil often is cheap insurance. According to the Chevron website, Delo-100 was formulated for 2 cycle diesels (Detroit Diesels)

Chevron Delo 100 Engine Oil
Chevron Delo 100 high-performance engine oils meet API service classifications CF-2 and CD-II (SAE 30, 40, 50) and CF and CD (all grades). These oils are designed to provide highly effective wear and deposits control in two-stroke diesel engines.
Delo: U.S., Canada & Mexico
 
#9 ·
"'Hit don't make no diff'erns"

Those are the words of a diesel mechanic I work with. And when pressed, I have to admit, he made some sense.

Modern diesels run about 500,000 miles between rebuilds. That's about 10,000 hours.
So if you motor at 5 knots you'd have to drive your boat around the world twice in order to create enough wear to create a rebuild situation.

Just follow manufacturer recommendations and change about twice a year - even if you haven't used the engine. That's because oil is hygroscopic and absorbs water over time.
And be sure you are using an oil intended for diesels - it'll have a "C" designation (for compression ignition) instead of an "S" (For spark ignition) like gasoline engine oil.
 
#13 ·
Denise, the "SAE" ratings are only relevant to one thing: How quickly does that oil flow through an SAE funnel at a specified temperature? Literally. That's all they measure, one temperature cold, one temperature hot, which is why some of them have a "W"inter rating as well as the single hot rating.

SAE ratings don't mean much.

The API "C" ratings for diesels ("C"ompression engines), and the "S" ("S"park)ratings are more important. A grade CD oil meets later specifications than a "CC" rated oil, and is obsoleted by a "CE" rating, etc. Same thing for the "S" series, the later in the alphabet that the second letter is, the newer the specs are. Sometimes that's not very relevant, but usually the later letter is the better product.

All oils with the same ratings aren't the same, but it is hard to find meaningful ways to compare besides reputation or brand name. Synthetic oils generally are built to higher standards, with added ingredients for better lubrication like molybdium sulfide dust, and the ability to provide "thin film lubrication" which protects your engine bearings during starting. The SAE specs don't rate those qualities at all.

So...any brand name you have faith in, that meets or exceeds the specs for your engine and the operating temperature range you will be running it in. If you want some fun, spend $25 on sending out an oil sample for testing once a year. The tests will show you if there is fuel or water or dirt contamination in the oil, along with trace metals that can warn you of bearing failures, etc. way before they are going to happen. Water contamination can come from simply not running the engine long enough and hot enough to cook off the normal condensation that forms in the oil, most of the sampling companies will tell you how to interpret their results.
 
#15 ·
Fascinating discussion, and one I'm very interested in right now. Especially MikeyMo's thoughts, since we own similar boats, but maybe not the same engines. I have just bought a Sabre 34-I (1979) with a Volvo MD11C, and the manual recommends 20W30. Can't find it anywhere (Pep Boys, Advance, WalMart, Sams, West). What do other users of Volvo's use?


Thanks,

Harry
1979 Sabre 34-I #063
Annapolis
 
#17 ·
Harry, you have a 1979 boat with a 1979 engine operating manual?

Put it in perspective. In 1979 oils did not perform the way they do today, oil additives broke down way faster than they do today. If your manual calls for 20W30, think about what that means. Your engine needs 30 for normal operation, and Volvo is saying that's too thick for cold starting.

Today's 0W40 and 5W30 oils DID NOT EXIST IN 1979! But they would be fine for your engine (provided they are C-rated, not just S-) today. Volvo probbaly would have spec'd a 5W30, IF IT HAD EXISTED IN A QUALITY OIL PRODUCT BACK IN 1979.

If you do a web search on what the SAE and API numbers mean, the mystery goes away. Does a redhead or a blonde make a better spouse? (SAE numbers and hair color are both about equally relevant today.)
 
#18 ·
HelloSailor, you hit on exactly my question. Yes, it's a 1979 engine. And, while I downloaded the manual this month, it's original to the vintage. And, yes, oil has come a LONG way in 30 years. I'm tempted to go with Rotella-T 15-40 (universally available high quality oil). The 40 is a touch thicker, but I doubt anyone will ever notice. And the startup at 15 would be nothing but good.

Harry
 
#19 ·
Paul, I'm aware of the issue--or, the allegation that there might be an issue--but AFAIK the only problem is that a "slipperier" synthetic oil may get past aging parts faster than a thicker cheap dino crude. The W-weight shouldn't be much of an issue, as the engine heats up pretty quickly. If the engine is simply not leaking because it is so old and gunked up...Yeah, you've got a point. Then again, an old oilburner that blows smoke can run for a long time burning a quart every two weeks instead of getting a ring and valve job. that still doesn't mean it shouldn't GET one.

Don't slinkies push themselves down the stairs? (VBG)
 
#20 ·
keep it clean!

:) Last I looked an atomic 4 was a gas engine:) but who cares? IMHO it is important to use C series oils in a diesel, Rotella being one of the better ones. 5 or 10 viscosity will leak thru a bad seal faster than 40, 40 will be harder to start, especially in cold weather. Within the same engine, temperature changes will determine the optimum viscosity, and as the engine ages and wears, a higher viscosity my become better because things don't fit as snug as they used to. Best place to start is from the owner's manual, but you will almost never hurt a diesel as long as you use a c series oil and change it regularly to keep it clean. Never go over 12 months on oil and filter, if you use it a lot change about 100 operating hours. Look at your dipstick daily, and don't panic if you just got your first diesel and see the oil is black! That's normal! Don't overfill, that is worse than running a pint low! Change it hot to get as much of that black gunk out as possible. An air leak or a clogged fuel filter will shut you down a lot sooner than oil. (I just spent the last two days cleaning a 30 year old diesel fuel tank):eek:
 
#21 ·
Don-
" Last I looked an atomic 4 was a gas engine but who cares?"
You missed the part about a VOLVO engine when I mentioned C-ratings, huh?

What, you've never seen the Volvo MD11 Atomic Engine? That's not surprising, they're usually painted all white and they're hard to spot in the average engine compartment.

(WEG)
 
#22 ·
Most engine oil seals are NBR or HNBR. Viton is much more expensive than the NBR/ HNBR compounds NBR can go colder before it stiffens up (cold gahman temp) but will heat age much faster than HNBR. HNBR is a more stable compound with higher heat exposures to 300F but typically can only go to -40C/F. Both compounds typically will have waxes (steric compounds)for oxone protection and plasticizers (oils) to assist in flexability and mold flow. Exposure to hot oil causes the elastomer to seek equalibrium, where the hot oil will displace a portion or all of the plasticizer. Changing from parafinitic to synthetic will cause the seal to again try to reach a new equalibrium and may alter the % swell as a result. The seal could gain volume or loose volume. If it shrinks, most probable, the % interferance of the lip to shaft can be reduced encouraging weapage/ leak.
 
#23 ·
I have a Volvo Penta MD7A on my 81 Islander 30. I have spent hours trying to figure out what oil to use. I have had the boat for a year and have not changed the oil (was changed just before I bought it). The book calls for 20 weight above 50F and 10 below that. I have talked to two authorized Volvo dealers in the area and two independant mechanics. No one, including volvo, make a straight 10 or 20 weight oil any more. They all say to use 30 weight. Volvo has some kind of online program to determine accessories, parts, oils, etc. but it is doesn't seem reliable - it said to use their 30 weight gas synthetic oil. All the mechanics I talked to recommended against a milti weight oil. I'll be using the straight 30 wt. for diesels.
 
#24 ·
I have heard it is not a good idea to switch to synthetic oil in older diesels. You can develop leaks. My new diesel car however came with synthetic from the factory and it specifies it in the manual. In my own experience when I switched to synthetic in an older generator it developed an oil leak. I like to use it for winters in my equipment but it seems to "evaporate" out of my older trucks v8motor as well.
 
#25 ·
I've been using the Shell Rotella-T 15-40 on the recommendation of several distributes for Yanmar Engines. Their alternate recommendation was straight 30 wt. With the CF-4 ratings it provides for improved control of piston deposits and oil consumption.
Be careful of using non diesel oils due to a lack of anti scuff additives like Zinc Dialkyl Dithio Phosphate. They took it out, large reduction of the stuff, due to being hard on the catalytic converter.
 
#26 ·
Yes, any good detergent oil (and "normal" oils today are all detergent oils) might eat away the crud that is masking leaking gaskets and seals in any old engine. And synthetic oil even more so, because it is simply more slippery than dino oil.

But this isn't the sixties, and oils have come a long way. If Volvo says "Use SAE10...use SAE20...you have to ask yourself what does that mean. The SAE numbers just mean how thick the oil is, and how long it will take--literally--to pour through a SAE standard test funnel. THAT'S ALL. It means nothing about lubrication properties, just "how thick is this goop?"

At low temperatures you want SAE10 or less because it will allow the camshaft to rotate sooner. When a cold engine starts, and there is no oil film built up around the shaft, the shaft literally slams from side to side (like a bowling ball in a clothes drier) in the bearings and they chew each other up.

Synthetic oils generally have better "thin film lubrication" properties than dino oil, meaning that even though there is only a thin film of yesterday's oil on the bearings, it still lubricates better than dino oil would. And in fact, the oil film can "get hard" when it is slammed, so it isn't displaced during startup as easily.

So they are saying, you need 10W oil or a lower rating in order for it to be thin enough to allow start-up lubrication in the cold. Today you can get 5W and even 0W rated oils for the same price as 15W50, and get even better protection during startups with no drawback. Thirty years ago, the drawback was that the additives and the sino oil broke down way faster when they pushed the specs that far, so the old oils wre not reliable or durable.

The new oils are.

The other side of the spec they are giving you is the 20-weight oil for normal temperature operation. That's pretty thin for a modern engine, it won't give much protection at high temps or speeds, but let's assume they want it for a reason. That would mean a 0W20 or 5W20 or 10W20 oil would be perfect for you, but I don't think you'll find it. Modern oils usually run to a #W-30 rating as the lowest.

What would that do to your engine? Well, again, a modern 30 will lubricate better than an old 20 would. It will be a little thicker, so if your engine has tight tolerances it might steal a little more power at speed. It might also need an oil pressure (pump) adjustment if it turned out the thicker oil pumped through slower. But given the way these are usually not critical parameters, and the other lube properties of modern oil...I think I'd trust it.

Of course you can always call a couple of pros, Shell, Mobil, Castrol, QuakerPenn, all have toll-free tech support and they will not tell you to put something wrong in your engine, because they generally warranty the engine against oil failure when you are using the product they recommend in it!

Obviously you need a diesel-rated oil, not a "spark" oil. Make sure to remind them of that. But I'll bet there are at least a half dozen suitable products out there, and unless your gaskets and seals are just waiting to fail anyway, synthetic oil shouldn't hurt them. If the makers say not to use them, that's something else again.

But Volvo? These days, who is Volvo? Ford? Tata Motors? An engineer, or a guy reading from a Customer Service Script Binder?

Check for the API and SAE web sites, and their explanation of just what their ratings do and don't mean. I think you'll find a huge fog (and burden) get lifted, and they do it very quickly.
 
#30 · (Edited)
As an example most of you are missing the point ........
If Volvo says "Use SAE10...use SAE20...you have to ask yourself what does that mean. The SAE numbers just mean how thick the oil is, and how long it will take--literally--to pour through a SAE standard test funnel. THAT'S ALL. It means nothing about lubrication properties, just "how thick is this goop?"
Engine oil is for more than just 'frictional lubrication'. The OIL is what maintains the clearance in the main and other HYDRODYNAMIC bearings in the engine. That SAE number is a correlation the viscosity of the oil; and the PROPER operating viscosity to develop the proper oil pressure IN the bearing journal is what supports the journals from crashing into the BEARINGS. If the original engine designer was clever enough to realize that the film strength of a certain viscosity oil was needed to support the bearing clearances under the maximum piston loads .... so why in hell would anyone think they are somehow (perhaps due to slick marketeering) smarter than the person who designed the clearances, load bearing ability of the bearings and then selected the VISCOSITY to keep the journals from crashing into the bearings ??????

The answer is stunningly and unbelievably simple: use the SAE viscosity and "Cx" rating that the engine manufacturer specified for the temperature (and rpm) ranges for that engine. All the rest is 'politics' and extreme hyperbole.

Next question: If my boats propeller is over-pitched (cant reach max rpm when under load) causing extreme combustion chamber pressure loads on the piston wrist pins and journal bearings should I increase the SAE number of the oil????? Answ.: Yes, one step higher is in order to keep the proper clearances when the engine is forced to 'lug' under extreme combustion chamber pressures.
 
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