What oil to use in old diesel engine?

[jmschmidt]

New diesel oil? Oh you mean lub oil.

[Sailorlady323]

Originally Posted by Bill O

PJ,
Where are you located? In a colder climate the multi weight oil is probably the way to go. In a warmer climate or tropics, a straight 30 or 40 wt oil was recommended in some older engines. The straight heavy wt. oil tends to stick to internal engine parts a bit more, which would be helpful during engine start up.

I have an old MD11C Always have used Rotella T1 30 vis that was what Volvo recommended.

[Shaneesprit]

Originally Posted by pjbori

Hello cruisers!

I'm about to embark on my first ever oil change on my new (old) cruiser. The engine is a 1975 Volvo Penta MD6A. The boat came with some extra oil, which was a 10W-40 (API SL/CF, ACEA A2/B2). The store I'm going to to buy new oil filter, and oil pump doesn't have oil with these specifications, so I'm wondering whether I can replace it with for example 15W-40?

Thanks in advance!
Cheers

I would look for B3 in the oil spec as a minimum.
B3 means it can cope in a turbo charged engine, so will ensure a better quality oil.
Some newer engines are using B4 but I have always like the B3 as a reliable guide.
Also buy from a known brand not a supermarket brand

[petter5]

This engine will be happy with most diesel engine oil's like 15-40 cd or better, but pure single grade SAE 30 oil is preferred, like Caterpillar part 198-7368
Cat® SAEO SAE 30

[CLASSEA]

Running Oil Type - Shell Rotella T4 SAE 15W-40 in my 1988 TAMD 41A . . .

[petter5]

TAMD 41 is a quite different engine with requirements for higher Grade oil than the old MD6A, so the Shell Rotella T4 SAE 15W-40 will also do fine in the MD6A.

[geoff3nebel]

Google the engine model and find the manual - there should be answer to your question

[parkstone bay]

On an engine like this, as many posters have already said, a "reasonable" - quality MINERAL oil labelled for diesel use. I stress "mineral" - you don't need synthetic, and the engine won't benefit.
One post said don't use "supermarket brand" (these are often reclaimed/ or high percentage reclaimed). Yes and no, I'd say. You really want an appropriate quality sump oil in service. But I've used a cheap supermarket brand for a couple of years as a flushing oil with success, on a 15 year old naturally-aspirated Bukh.
Run the engine up to temperature with the old oil, and drain. At this stage, don't change the filter. Refill with budget/supermarket oil. Keep this in for an hour or so's running, drain this, then go for the better stuff; Rotella, Rimula, known-name brands are all ok; then change the filter. In Scandinavia, you might need a low "winter" number, if you're going to use the boat when it's cold. But when I was in Oslo in the 1980's, nearly everyone took their boats out before the fjord froze.
Some final thoughts: 1. it's always good plan to leave the engine with nice clean oil (even supermarket stuff) over the winter, rather than old oil, which is slightly acidic. 2. Ensure the fuel tank is full to reduce condensation. 3. Replace the water impeller at the BEGINNING of the season, rather than at winter lay-up. 4. If you can, get down to the boat once or twice during the winter, and turn the engine over by hand one or two revolutions. 5. If you do leave anything in such a state that the engine cannot be started, (fuel lines off, etc), leave yourself a conspicuous note, so you don't forget in the spring. Trust me, it happens!!

[capemiker]

I use straight 40w synthetic, cuts down on smoke!

[petter5]

Originally Posted by capemiker

I use straight 40w synthetic, cuts down on smoke!

Absolutely not, these old Diesel engines will not be happy with synthetic oil.


Single grade 30 oil as stated above is to prefer, but they will also run fine with any modern 15-40 mineral oil.

[capemiker]

I totally disagree,
Running like a switch watch, no problem with seals, all good!

[BBill]

Use oil speced for diesels. Don't even think of using regular car oil. I was helping deliver a Yamar powered sailboat about 40 yrs ago. Dinner Key, Miami to Key West. The owner changed the oil at Dinner Key and the engine started chugging about halfway down near Newfound Hbr. It was smoking, laboring and hardly turning over past idle rpms. Ended up he used regular car oil and it thickened up like heavy syrup...bordering on pudding. Newbie owner didn't know better. We changed the oil to the diesel stuff and contiunued without a problem. The engine survived a cruise through the Bahamas and several more yrs of service.

[Icarus]

In an older engines 15-40 is quite ok.

[sailingharry]

I had an MD11C, big brother tier engine. I wrestled with what viscosity oil to use, because the specified oils didn't exist. I came to the conclusion that they didn't specify multigrade oils because they hadn't been invented back then. I looked at what they recommended, and came to the conclusion that 10w30 is what they would have recommended if it existed. A little harder to find than the common 15w40, but Rotella makes it and you can get it.

[tkeithlu]

Whoa. Not "any" 15W-40.

Rather than trade limited experiences as gospel, let's stick to the SAE and API ratings. They are based on extensive testing and knowledge of the molecules involved. The basic qualifier is that it be "C" oil, not "S" oil, because lots of "S" oil can't take the beating of a high compression diesel engine, ergo the syrup above. Letters following the S or C refer to later standards within the general classification, such that your car may require an SF, not just an SE, or similar. Same goes for modern diesels.

Being multigrade is a different dimension in the testing. Long ago, no multigrade could manage to earn a "C" rating, but more recently that problem has been overcome, ergo 15W-40 Rotella and the like. This rating just means that the oil has the liquidity/lubricating qualities of a 15 grade oil at cold temperatures and still the lubricating qualities of a 40 grade oil at high temperatures.

You can buy oil by its ratings. Whether it came from a big box store or an automobile racing dealer, you engine will respond to the rating, not to the cable TV ads. If you have an older diesel engine, you are not going to find "C" oil anywhere on the shelves that does not meet your engine's needs, because no one produces an oil that is only OK for old engines. Just read the label and go sailing.