SailNet Community

SailNet Community (
-   Diesel (
-   -   Oil! (

deniseO30 06-15-2009 01:38 PM

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:

GreatWhite 06-15-2009 01:52 PM

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

erps 06-15-2009 03:23 PM

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.

JiffyLube 06-15-2009 03:34 PM

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.

wwilson 06-15-2009 03:45 PM


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.


sailingfool 06-15-2009 03:48 PM

54 Attachment(s)
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."

erps 06-15-2009 03:49 PM

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

mgmhead 06-15-2009 05:15 PM

My boat gets only Shell Rotella 15-40. That's what the PO used for 10-years and he was on the Shell team that developed Rotella...if he believes in it, I believe in it. I'd be a fool to change.


Selkirk 06-15-2009 07:43 PM

"'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.

deniseO30 06-15-2009 09:35 PM

thank the sea gods at least my diesel is ok... can't say dat bout me!

All times are GMT -4. The time now is 08:44 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
(c) LLC 2000-2012

For the best viewing experience please update your browser to Google Chrome