M25XP - what type oil?

Stu Jackson · Aug 3, 2014

uwyoda said:
..but have been told by someone...

Usually the kiss of death. If it works for you don't switch. You can find out about oil weights and combos using Google.

Joetech · Aug 3, 2014

Not much difference between 10w40 and 15w40. These are multi-viscosity oils which means they act like 10 or 15 weight (light viscosity oils at low temps and maintain 40 weight, median viscosity oil at operating temps). I have an 86 Universal M-18 and the manual specifies SAE 30. Good luck finding a single weight oil these days. I have 315 hours on this engine. Almost nothing on a diesel. Marine diesels run cool compared to their tractor counterparts. Universals use Kabotu engine blocks and heads and other parts. If it ain't broke don't fix it. Too thin of an oil will get past the rings and burn. Too thick and it won't get into the thin passages at start up and engine wear is the results.

Alan Gomes · Aug 3, 2014

bhstech said:
I have an 86 Universal M-18 and the manual specifies SAE 30. Good luck finding a single weight oil these days.

West Marine sells it.

Stu Jackson · Aug 3, 2014

Alan Gomes said:
West Marine sells it.

True, but for the same reason I don't suggest anyone buys a battery from WM, check the price. The auto store down the road will beat it all the time. Don't use synthetics on an older diesel either, it eats the seals. And whether anyone thinks that's true or not, it simply isn't worth the risk. Dino oil is just fine.

And here's one of the best bits of M25 series engine info around:

http://www.c34.org/wiki/index.php?title=Diesel_Engine

Alan Gomes · Aug 3, 2014

Stu Jackson said:
True, but for the same reason I don't suggest anyone buys a battery from WM, check the price. The auto store down the road will beat it all the time.

But the point to which I was responding is that the auto parts store down the road doesn't always carry straight 30 wt. West Marine is always an option if one can't find it elsewhere. My local Captain's Locker has it cheaper and that's where I tend to buy it myself.

jimg · Aug 3, 2014

Actually Universal now calls for SAE 30 OR 10w40. There is zero benefit to using a straight 30 weight. Use the 10w40, and as already mentioned 15w40 is not that much different.

jrowan · Aug 4, 2014

uwyoda said:
I have been using 10W40 engine oil, but have been told by someone that due to the age of the engine (1988 model Universal M25XP) that I should be using 15W40 instead. I have no clue what the difference is between 10W and 15W and would appreciate any enlightenment/suggestions.
Thanks!

ps. I have been using Shell Rotella 10-40 weight heavy duty oil made specifically for diesel engines for the past 20 years & it has never let me down.
It is a very durable oil against thermal breakdown, & I know several marine mechanics who swear by it.

The more likely culprit for eventual overheating of any engine is the water pump impeller failure. Anytime I've ever had an overheating problem, it was always a problem with the water pump, not engine oil. Change your impeller regularly & save your money by buying standard oil, not synthetic. Cheers.

Hayden Watson · Aug 4, 2014

jrowan said:
ps. I have been using Shell Rotella 10-40 weight heavy duty oil made specifically for diesel engines for the past 20 years & it has never let me down.
It is a very durable oil against thermal breakdown, & I know several marine mechanics who swear by it. QUOTE]

You should also make sure that the oil you are buying is for the type of engine you will use it in. API has two basic service types for motor oil. S for spark (gas) and C for compression (diesel). In the top half of the "API Donut" you will find the type. It will say "API SERVICE S*" or "API SERVICE C*". The * will tell which revision of the type spec is used in this oil. in the center of the API Donut is the weight grade.
For a Diesel engine made in the mid 80's you need to look for a CE grade oil or above. The current spec is CJ4 which is formulated for low sulfur fuels and wear control.

The two most common C types are Rotella-T and Delo 400.

Ward H · Aug 6, 2014

I do not own a diesel powered boat, yet, but do have a quick question.
For marine recreational diesels, do you have testing done on the oil to check the condition of the engine? I do not remember seeing that subject in threads.

Stu Jackson · Aug 6, 2014

Ward, yes, it is a good idea. There are two types of tests:

--- a one-off, which will show if there's any solid particles and be a baseline for future oil samples

--- followups which use the baseline and then see if the condition of the oil has changed

Anyone who suggests that a single oil sample, which doesn't show any particles, has any meaning may not understand the whole concept.

And while boat surveys are usually recommended, and necessary sometimes for insurance purposes, they usually don't do engines, so a separate engine survey would be suggested for new owners if they don't know anything about diesels.

And, yes, Virginia, diesel engines take different oil than gas engines.

Jethro411 · Aug 6, 2014

Never mind

Stu Jackson · Aug 6, 2014

I'm pretty sure all diesel engine service manuals talk about using the proper oil. I'm sorry you may not have had the chance to read yours yet.

Look, we ALL were new to this stuff when we bought our boats. I was NOT born a diesel mechanic, or an electrician or a plumber.

I read, I learned. And I admit I'm old enough to have had the "pleasure" of doing all this before the blinkin' internet, which has, most will admit, made it waaay easier.

I wish you all the luck, but luck has nothing to do with it, it takes effort and a lot of reading, 'cuz you can't get all the answers in one thread on one boating forum.

I may have mentioned that we have, on our C34 website, assembled

Engines 101 - The BIGGEST & BEST collection of Universal Engine Information on the Internet

http://www.c34.org/wiki/index.php?title=Diesel_Engine

Please, feel free to avail yourself of it. It's taken many skippers many years to assemble the information, and we certainly hope it will save new skippers years of effort and $$.

We share as much as we can, but we've said it before: "We can make it available, but we can't make folks read it or even act on it."

I'm sure you, OTOH, will.

MORNING LIGHT · Dec 6, 2014

Thanks Stu , now I got my mind made up !!

Ben

chrisings · Dec 6, 2014

Hayden Watson said:
jrowan said:

ps. I have been using Shell Rotella 10-40 weight heavy duty oil made specifically for diesel engines for the past 20 years & it has never let me down.
It is a very durable oil against thermal breakdown, & I know several marine mechanics who swear by it. QUOTE]

You should also make sure that the oil you are buying is for the type of engine you will use it in. API has two basic service types for motor oil. S for spark (gas) and C for compression (diesel). In the top half of the "API Donut" you will find the type. It will say "API SERVICE S*" or "API SERVICE C*". The * will tell which revision of the type spec is used in this oil. in the center of the API Donut is the weight grade.
For a Diesel engine made in the mid 80's you need to look for a CE grade oil or above. The current spec is CJ4 which is formulated for low sulfur fuels and wear control.

The two most common C types are Rotella-T and Delo 400.

Click to expand

Yes, yes a thousand times yes!! The type of oil is far more important then the weight. As others have said 10w40 and 15w40 are so close it would not matter. On the other hand if your oil does not have the proper additives to handle the blow by byproducts of diesel combustion engines you'll have no lubrication properties left in no time at all.

Charles Erwin · Dec 6, 2014

This might help

http://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx

gregorybross · Dec 8, 2014

I use Delo 400LE 15-40. It's designed for diesel engines and I have been very happy with it. Costco sells it for a good price. My engine is a 25xp.
Greg