15w-40 in my boat, is diesel oil OK?

[chriscpmtmp]

My boat calls for 15W40. Synthetic is not required. It is a waterski boat. The thick grade is presumably because of the high loads when we start. A typical set is 6-8 30 second runs with a one minute break. 20 minutes total. So floor it, level out at 3600 rpm, then stop, wait. Turn around and do it again.

I know a lot of guys run thinner Mobil 1 - like 5w30. That seems like a bad idea when 15w40 is stamped right on the oil cap.

Someone online had good luck with Rotella T5 15W-40. I did my pre-season oil change before I realized that this is diesel oil. Hmm. So the grade is correct, but are there additives that are bad for my engine? This is a v8 350. It does have cats.

I debating - should I leave it or change it?

 

[zrxkawboy]

Welcome to BITOG!

The Rotella will be fine, especially since your engine calls for 15W40. I'm not aware of any 15W40 oils that AREN'T diesel oils. Besides, most are dual-rated (for diesel and gas applications).

 

[demarpaint]

Welcome to Bitog! We've used HDEO 10W40 in a 351 Ford V8 w/o problems for many years. No CC though.

 

[Donald]

Many people use Rotella T 15W40. It should be both diesel and gas rated.

 

[yvon_la]

cj-4 oil are designed for engine with total sulfur content of max .5 % so no you likely cant use that oil if it is a sn/cj-4 oil

you ll damage your engine

 

[CarbonSteel]

Originally Posted By: yvon_la
cj-4 oil are designed for engine with total sulfur content of max .5 % so no you likely cant use that oil if it is a sn/cj-4 oil

you ll damage your engine
Huh? All 15W-40 oils carry dual specifications for diesel and gasoline engines. How will the OP damage his engine by using this oil? I have not seen any CJ-4 oil that has less than an SM gasoline rating and that will hardly damage a gasoline engine as SM was being used in 2010/2011 gasoline engines. You should clarify your meaning so it is not incorrect or taken out of context. OP - these oils will be fine for your application.

 

[alarmguy]

Originally Posted By: chriscpmtmp
My boat calls for 15W40. Synthetic is not required. It is a waterski boat. The thick grade is presumably because of the high loads when we start. A typical set is 6-8 30 second runs with a one minute break. 20 minutes total. So floor it, level out at 3600 rpm, then stop, wait. Turn around and do it again.

I know a lot of guys run thinner Mobil 1 - like 5w30. That seems like a bad idea when 15w40 is stamped right on the oil cap.

Someone online had good luck with Rotella T5 15W-40. I did my pre-season oil change before I realized that this is diesel oil. Hmm. So the grade is correct, but are there additives that are bad for my engine? This is a v8 350. It does have cats.

I debating - should I leave it or change it?


Of course, yes, you can use the Rotella 15/40 or ANY other 15/40.
A very common misconception is "diesel" motor oil is just for diesel engines.

Not true. Diesel oil is simply a beefed up "automotive" oil. In fact, if you look at the back of the container it will still state and show the API symbol of not only the diesel API rating but also the Automotive API rating for use in gasoline engines.
In most cases its API SM or SN PLUS the diesel rating of CJ4.

For whatever it is worth, without question, the Rotella is far better for your engine then any automotive only engine oil.
The Rotella is rated for automotive gas engines PLUS the extra heavy duty rating for diesel engines. This is PERFECT for watercraft engines, the extra additives keep corrosion under control as well.

 

[A_Harman]

I don't know of any 15w40's that are only gasoline-rated that are available in the USA. The best you can do if buying oil at WalMart is a dual-rated diesel oil, probably rated CJ4/SM. Maybe there are some oils sold by marine engine manufacturers that are 15w40, but they would be very expensive. I think Mercury Marine has a 20w40 gasoline engine oil.

Or, here's one from Indmar, but it's dual-rated:
http://www.indmar.com/Genuine_Indmar_Service_Products/Lubricants.aspx

A good gasoline-rated oil that's available everyday at WalMart would be Mobil 1 High Mileage 10w40.

 

[DriveHard]

Historically I have always run Delvac 15w-40 in my marine engines. Always had good success spanning from a 5.0, custom 5.7, 7.4, and my most recent 5.7L engines.

Right now I am running Synthetic Blend Mystic 15w-50 because I got a great deal at my local farm store for a 5 gallon bucket for $50.

 

[Rand]

Originally Posted By: yvon_la
cj-4 oil are designed for engine with total sulfur content of max .5 % so no you likely cant use that oil if it is a sn/cj-4 oil

you ll damage your engine


Please quit posting bad information.

 

[Pontual]

Gas is below 500 ppm sulphur, anyway.

 

[Quattro Pete]

Originally Posted By: yvon_la
cj-4 oil are designed for engine with total sulfur content of max .5 %

First of all, the API CJ-4 diesel fuel sulfur content limit is 0.05%, not 0.5%.

0.05% = 500 ppm.

And this limit is specifically related to diesel fuel, not gasoline.

Second of all, today's diesel and gasoline has sulfur content which is significantly below this 500 ppm limit.

 

[Schmoe]

leave it. I have a 3.0 and use Delvac 15W-40. The main reason for using the "thicker" oil is that on a boat engine, it constantly gets a workout. there is no coasting like a car engine. It is always under the load and oil will shear faster than on a car engine, hence, the beefier stuff is your friend on the water. Diesel oils historically have a stouter additive package and that is what you want on your boat engine, especially running it like you do. I'd also let it idle down a few minutes before you shut it off. Use it with confidence and have some fun!!!

 

[toneydoc]

you can read and study them at petroleum quality institute of America website. you will find lots of good info there

 

[chriscpmtmp]

Thanks for all the comments. Yo guys are a wealth of information.

The one this I'm wondering is that the packaging for the Rotella does not list SM or SN Plus. Is this a concern?

Here is a pic:

Originally Posted By: alarmguy

Not true. Diesel oil is simply a beefed up "automotive" oil. In fact, if you look at the back of the container it will still state and show the API symbol of not only the diesel API rating but also the Automotive API rating for use in gasoline engines.
In most cases its API SM or SN PLUS the diesel rating of CJ4.

For whatever it is worth, without question, the Rotella is far better for your engine then any automotive only engine oil.
The Rotella is rated for automotive gas engines PLUS the extra heavy duty rating for diesel engines. This is PERFECT for watercraft engines, the extra additives keep corrosion under control as well.

 

[chriscpmtmp]

Opps. I see the SM. I'm a dope.

So I think I'm good.

 

[alarmguy]

Yes, your good! )

BTW Rotella is a great oil, as is just about any of the 15/40 oils out there from Mobile Delvac, Delo, Valvoline etc. Even Walmarts supertech brand is all good in the 15/40 HEDO.

But yes, my "feel good" choice would be the Rotella or Delvac for your purpose but you cant go wrong with any of them.

 

[callbay]

Originally Posted By: A_Harman
I don't know of any 15w40's that are only gasoline-rated that are available in the USA. The best you can do if buying oil at WalMart is a dual-rated diesel oil, probably rated CJ4/SM. Maybe there are some oils sold by marine engine manufacturers that are 15w40, but they would be very expensive. I think Mercury Marine has a 20w40 gasoline engine oil.

Or, here's one from Indmar, but it's dual-rated:
http://www.indmar.com/Genuine_Indmar_Service_Products/Lubricants.aspx

A good gasoline-rated oil that's available everyday at WalMart would be Mobil 1 High Mileage 10w40.


On the Indmar wedsite it list recommended 15-50 full synthetic made by Exxon Mobil.

I wonder if it is the same as the Mobil 1 15-50 full synthetic?

 

[akcooper9]

I run Delvac 1300 in our MPI 5.0 and am very happy with it.

 

[CT8]

Originally Posted By: chriscpmtmp
Opps. I see the SM. I'm a dope.

So I think I'm good.
I am a dope as well. Don't fret cause after a dozen or so years you just accept the fact. The oil will work great in a marine engine. The HDEO oils are what most commercial users run in their gas and diesel powered boats. 20W-50 conventional or 15W-50 syn also works well. you don't need a 5W- what ever oil though.