What oil do you use in your engine?

[IDBoating]

I have the PCM EX-343 engine. The owner's manual says to use 15W-40 oil rated for GF-4/SM service. I use 15W-40 in my Cummins diesel engines, and after visiting my local auto supply house today it appears that ALL 15W-40 oil is rated for diesel use - NOT gasoline. The ratings are different than GF-4/SM (for example, the S indicates gasoline service).

The PCM manual says in 50F and below you can drop to 5W-30. But that's not the prevailing temperature when I'm using the boat.

I'm thinking perhaps going to 10W-40 (possibly the most common oil out there) but the manual doesn't actually say to use it.

What does everyone here use? Thanks!

[chpthril]

You should find the recommended 15W-40 at your local marine supply. Merc and Pennzoil offer it, West Marine has it under their own label,

[whitlock87]

I have a Marine Power, and it uses HD 30.

[Joeprunc]

I've got the old 350 Mag MPI I use Chevron HD 30wt. I had a really good sludge problem from using Penzoil in another car (it was always the cheapest oil), but I'm sure their Marine grade is 100 Xs better.

[IDBoating]

Tried NAPA this morning - no luck.

To their credit, they called Pennzoil while I stood there to ask them the question. Their statement was that 15W-40 diesel-rated (CJ) oil is perfectly acceptable. I have sent an email via PCM's website "Contact Us" mechanism asking if they agree with that... we'll see if they respond. (I have two pending website questions with them. They have never responded yet, but I continue to be hopeful. Funny that they have the "Contact Us" mechanism but seem to ignore it.)

[IDBoating]

From Mobil's website...

>>From an engine performance viewpoint, the API CJ-4 oil should provide adequate protection. But this heavy-duty viscosity grade has a higher level of phosphorus than typical ILSAC GF-4/API SM oils designed for today’s light-duty trucks and cars. This higher phosphorus level can potentially shorten the life of expensive emission control equipment including the catalytic converter. We recommend you stick with the oil recommended in your owner’s manual.<<

...from:

https://www.mobiloil.com/USA-English...s_Engines.aspx

So it may work great in normal exhaust engines, but my in CAT equipped engine it doesn't sound like the best choice.

[chpthril]

Just an FYI about oil: if the jug says "Heavy Duty" it's all marketing. The weight and API codes on the back tell the story. If it has "HD" printed on the label, that stands for "High Detergent" not heavy duty and is there to represent the higher levels of cleaners in the oil as compared to std detergent motor oil. HD oils are more commonly used for diesel engines.

[IDBoating]

Just an FYI about oil: if the jug says "Heavy Duty" it's all marketing. The weight and API codes on the back tell the story.

Agreed. Ignore the hype, read the specs.

If it has "HD" printed on the label, that stands for "High Detergent" not heavy duty and is there to represent the higher levels of cleaners in the oil as compared to std detergent motor oil. HD oils are more commonly used for diesel engines.

FWIW, PCM's manual specifically recommends AGAINST low- or no-detergent oils.

[chpthril]

Agreed. Ignore the hype, read the specs.



FWIW, PCM's manual specifically recommends AGAINST low- or no-detergent oils.

Correct, low or non-detergent oils should not be used in internal combustion engines IMO, but oil that is NOT an HD, doesnt it mean it's a low or non-detergent. If one purchased their oil based on the correct API rating, it would be hard to walk out of the store with a low or non-detergent oil for your internal combustion engine.

[turbonine]

PCM and Indmar both recommend using 15W-40, which has the C rating for diesel. They prefer this because it has more detergents than a S rating oil. I have always used Shell Rotella in my boat. Makes buying oil easy since that is what I use in my Powerstroke also.

The important thing to remember is to let your engine warm up prior to putting any load on it. I usally keep mine at idle until I reach at least 140.

[IDBoating]

PCM and Indmar both recommend using 15W-40, which has the C rating for diesel. They prefer this because it has more detergents than a S rating oil.

Actually, they specifically require an SM rated oil. Here's the quote from the PCM manual:

The following chart shows the recommended oil viscosity
for various ambient temperature ranges:
Prevailing Ambient Recommended A.P.I.
Temperature Classification & Viscosity
Above 50°F SAE 15W-40 “GF-4/SM”
Below 50°F SAE 5W-30 “GF-4/SM”
IMPORTANT: The use of oils which contain “solid”
additives, non-detergent oils or low quality oils
specifically are not recommended.

WARRANTY NOTICE: PCM Engines reserves the right
to refuse warranty on part(s) and/or engine(s) damaged
by using improper fuels and engine oils.

[turbonine]

Actually, they specifically require an SM rated oil. Here's the quote from the PCM manual:

I just went to the garage and looked at a bottle of Mobil Delvac and a bottle of Rotella. Both had an SM rating.. Even Chevron Delo has it.

[IDBoating]

I just went to the garage and looked at a bottle of Mobil Delvac and a bottle of Rotella. Both had an SM rating.. Even Chevron Delo has it.

But do they have the GF-4 rating as well?

Some of the on-shelf oils even have the newest GF-5 rating now. GF-5 is specifically backwards compatible with GF-4.

It has been suggested that diesel oils have an additive package that is not recommended for engines with catalytic exhaust systems. I have a CAT-equipped EX-343 so the CJ rated oils may not be a good choice.

BTW, we may have an authoritative answer soon. I finally (hooray!) reached a live person named Deborah at PCM who started digging into this question. Apparently the 15W-40 GF-4/SM requirement isn't theirs, but GM's (from whom PCM buys the engine blocks). According to Deborah, PCM is aware that the exact oil is very difficult to find. She now has one of their Engineers asking GM for clarification. She has promised to call me back on my cellphone with an answer that specifically addresses this issue for my CAT-equipped engine.

[chpthril]

But do they have the GF-4 rating as well?

Some of the on-shelf oils even have the newest GF-5 rating now. GF-5 is specifically backwards compatible with GF-4.

It has been suggested that diesel oils have an additive package that is not recommended for engines with catalytic exhaust systems. I have a CAT-equipped EX-343 so the CJ rated oils may not be a good choice.

BTW, we may have an authoritative answer soon. I finally (hooray!) reached a live person named Deborah at PCM who started digging into this question. Apparently the 15W-40 GF-4/SM requirement isn't theirs, but GM's (from whom PCM buys the engine blocks). According to Deborah, PCM is aware that the exact oil is very difficult to find. She now has one of their Engineers asking GM for clarification. She has promised to call me back on my cellphone with an answer that specifically addresses this issue for my CAT-equipped engine.

Hard to find? I can drive a mile up the road and buy it at a local mom'n pop marina and 20 minutes down the road @ West Marine. It's hard to find because it's not a weight that is common for autos and like gas trucks, but is more common for diesels, but you will find it in a marine grade. I did see where you stated you wanted it in the auto-grade, why not marine?

[IDBoating]

Hard to find? I can drive a mile up the road and buy it at a local mom'n pop marina and 20 minutes down the road @ West Marine. It's hard to find because it's not a weight that is common for autos and like gas trucks, but is more common for diesels, but you will find it in a marine grade.

I took your advice and looked it up on the West Marine website. There it was, just as you said. So was a Pennzoil 15W-40 marine product. So I called my local West Marine and had them go grab a bottle off the shelf and read the label to me on the phone. Guess what - it's C* rated oil, meant for diesel applications. It is not SM rated oil. Same problem as all the others.

I looked up the Pennzoil product on Pennzoil's website and it, too, is a diesel rated oil with a C* rating. It's a marine oil, yes, but marine diesel.

I'm waiting for the call back from Deborah at PCM.