New to Diesel Engines quetion about Oil Ratings

[John Kandris]

Good Day Fellow Catalina Folks,

We are the new owners of Sailaway (as she currently named) 1986 Catalina 34 Hull #95.  She has a M-25 installed.  My question is this.  I have dug around in the documentation and have understand that the oil type should be either straight 30 or 10w-30 with a CG-4 rating (which is obsolete)  What is everyone using oil wise.  I'm having trouble finding this rating or am I just missing it.  I just dont want to screw this engine up.

Any help would be amazing.  Thank you everyone.  3 weeks to splash.  I cant wait to get her back out in the water.

John

[waughoo]

I use Chevron Delo ("De"iesel "L"ubricating "O"il).  I am not sure if it meeta the spec you mention, but it was what I used in all the diesels I maintained prior to the boat.

[John Kandris]

Thank you. Which weight do you use?

[Jon W]

I've been using Shell Rotella T4 which is 15w-40.

[Stu Jackson]

I have an M25 in our boat.  I have used various oils over the years, engine is still running fine.  Don't over think this.  The M25 engine manual specifies oil ratings that simply aren't made anymore.  Why?  Because they have been superseded by better oils.  If you live in a cool climate, multi-weight oil will work better on startup than heavier single weight oil.  Just make sure you purchase diesel engine oil.

[Patches]

Been using Walmart "Hi-Tech" 15W-40, Heavy Duty diesel oil since I bought the boat in 2018.  I like the size of the gallon container (small), the price (cheap), and usually store it in the V berth in the bottom tip out cabinet under the drawers.

Don't know about others, but an oil and filter change on my M25-xp uses exactly one gallon of this oil, which makes things very simple.

Patches

[KWKloeber]

John

Engine oil is a hot button topic! 

The (seems to me) majority tend to put their faith in (Shell) Rotella (one of its dino oils) or a synthetic like Mobil 1.  There's some (unsettled) controversy over whether a synthetic is the best choice for an older diesel, so I say "why chance it?" (synthetic) when a plain ol' dino oil does just as well -- I'm not in need of longer oil longevity. 

Others don't care and use the synthetic.  But it's noteworthy, I think anyway, that Kubota itself sells oils that are listed as suitable for our (tractor) engines and none of them are synthetic.   As far as conventional Dino oil, Rotella T1 (single grade) or T4 (multigrade) are good choices. 
I stay away from other Rotella "T"s that may be formulated for over-the-road heavy truck use and may have additives that are not healthy for our engines.

Fact:  The oil formulation has changed because engines have evolved and emission standards change.
Fact:  My engine hasn't changed since the day it was installed.
So the oil that is nearest the one that Kubota recommended at that time is what I go for.  Right now that's CK-4 dino like Rotella T-1 30 weight.

Some oil reading:
https://26ed2d06-9e49-4586-8f39-2a05f982162e.filesusr.com/ugd/3bd504_eec473b8b1144dccb338ca2cd51b9dbc.pdf

[Ron Hill]

Guys : In conversation with the Mobile 1 Engineers, they recommend that you NOT mix brands of "C" rating oils - because the different additives can clash!!

A thought

[Holger Dieske]

.. a few years ago I spoke to an old diesel mechanic from East Germany who has been working on these simple, old diesel engines all his life. He said that the new synthetic oils are not so good for these old engines and recommended that I use plain mineral oils. I use Valvoline All Fleet 15W-40.

Holger

[John Kandris]

Wow, now that is why a love a community.  Thank you all very much.  That was one hell of an answer.  I live on a Mainship 36 with old crusader engine and they are a bit finicky when it comes to oil so I went with the only stupid question is the one not asked.

Honestly, I was way over thinking it.  Stupid ADD and hyper focus.  3 weeks to splash and I cant wait..

[KWKloeber]

John
My bro has a MS34 "Bacchus" - loves it!

You got off easy, I think the last oil debate was 40 replies!!