15w40 dual rated oil instead of 5w30 Gasoline Engine oil.

[Foxtrot08]

Diesel oils don’t have the same ZDDP limits as PCEOs, and usually has higher TBN as well. Lake Speed Jr wrote something about diesel oils having different anti-foaming agents that “may” cause issues in gas engines because of RPM, but I don’t know if that’s true- I’ve never personally seen any data to substantiate his claim, but I’m also not an oil formulator.

@High Performance Lubricants, @Foxtrot08, or @MolaKule: is there any truth that HDEO anti-foaming agents can cause issues because of the higher RPM range in auto applications?

It’s not really a “different” anti foam, it’s just less of it.

A diesel engine oil has significantly more dispersants typically, as the main concern in a diesel engine oil is soot load. Soot loading will typically be why a diesel engine oil reaches end of service. Other than something catastrophic/mechanical like fuel dilution.

Along with the lower RPM, you’ll generally see less foam.

Gasoline engines will have more foaming for a plethora of reasons. Higher engine speeds, higher temps, more on/off cycles, running cold more often. (See the on/off cycles) Which can lead to moisture issues. Fuel differences (ethanol fuel blow by gathering moisture.) Etc. Etc.

Generally, gasoline engines are more prone to foaming.

Since you only have X amount of additive space in a blend, and you want Y end properties of the engine oil, you have to balance what you put in the additives. Thus you set your primary goals and go towards that. Balancing your detergents, dispersants, antioxidants, your VII, cold flow improvers, friction modifiers, etc. etc. etc. is the “magic” behind different blends as we’ve seen here. If you just load up with additives, you’re going to see negative results in other directions.

 

[SubieRubyRoo]

Thanks Fox!!

 

[ARCOgraphite]

I'm in FLA, no such thing as a cold start here.. and I have a considerable supply of 15W40 on hand, which carries the SN cert as well as the CK rating... so is there any real point in purchasing and using the recommended 5w30 or does it make sense to use the 15w40 since I have plenty of it and it make the oil change free.. I dont think it makes any difference but it would be interesting to read some of the commentary and doom and gloom.

I tried 15W40 in a Subaru EJ - and engine that could handle it. It was too thick ( high HTHS ~4.3 cP) and the motor didn't like it generally - mileage, response and drive-ability dropped WAY off..

I would run a 10W30. QS full synthetic 10W30 is my go to Spring thru Fall in 20 grade spec vehicles.

Stay FAR AWAY from typical high VM laden 10W40.

The move into a a higher HTHS oil should be a 5w30 Euro oil or a marginal 30 grade lubricant such as ACEA 0W40 or 5W40 like M1 FS or other Euro equivalents with MB and Porsche certs,

KV100 doesn't matter, the in situ resultant HTHS is whats boss.

 

[Fahrvergnügen]

The main difference is the diesel oils have more detergents and a greater ability to hold soot in suspension.
They also have higher zinc and phosphorus levels.

There is more to it than that.

Is Diesel Motor Oil the Right Choice for a Gasoline Engine?

Many enthusiasts look to diesel motor oil as a high-zinc alternative, but is it the best choice? A certified lubrication expert explains the difference.

www.motortrend.com

 

[Lubener]

I don't think it's a good idea using 15w-40 and having a catalytic converter.

 

[Rygrego]

I'm in FLA, no such thing as a cold start here.. and I have a considerable supply of 15W40 on hand, which carries the SN cert as well as the CK rating... so is there any real point in purchasing and using the recommended 5w30 or does it make sense to use the 15w40 since I have plenty of it and it make the oil change free.. I dont think it makes any difference but it would be interesting to read some of the commentary and doom and gloom.

You'll be fine, I would use it without a worry. Also if you see a perceivable difference in mileage I would be shocked. No worry about warranty as in my 40 years working at new car dealerships not once was an engine replacement contingent on oil viscosity grade, just lack of oil changes.

 

[PoorMans180SX]

It's very clear people are commenting on this thread without reading any of the previous comments.

 

[RooflessVW]

It's very clear people are commenting on this thread without reading any of the previous comments.

Or without knowing what the hell they're talking about, in general.

 

[RooflessVW]

I don't know what car or which engine you have but I would (and have) used HDEO in a variety of applications, including my 996, my Touareg TDI, and a very large number of old European/Japanese cars.

 

[53' Stude]

Or without knowing what the hell they're talking about, in general.

Hey now, don’t threaten me with a fun time

 

[userfriendly]

I tried 15W40 in a Subaru EJ - and engine that could handle it. It was too thick ( high HTHS ~4.3 cP) and the motor didn't like it generally - mileage, response and drive-ability dropped WAY off..

I would run a 10W30. QS full synthetic 10W30 is my go to Spring thru Fall in 20 grade spec vehicles.

Stay FAR AWAY from typical high VM laden 10W40.

The move into a a higher HTHS oil should be a 5w30 Euro oil or a marginal 30 grade lubricant such as ACEA 0W40 or 5W40 like M1 FS or other Euro equivalents with MB and Porsche certs,

KV100 doesn't matter, the in situ resultant HTHS is whats boss.

How is 10w40 "VM laden" but not 0w40 or 5w40?

 

[Rygrego]

I don't think it's a good idea using 15w-40 and having a catalytic converter.

The only time it's an issue is if you're burning a lot of oil otherwise no problems.

 

[MolaKule]

Diesel oils don’t have the same ZDDP limits as PCEOs, and usually has higher TBN as well. Lake Speed Jr wrote something about diesel oils having different anti-foaming agents that “may” cause issues in gas engines because of RPM, but I don’t know if that’s true- I’ve never personally seen any data to substantiate his claim, but I’m also not an oil formulator.

Neither have I as anti-foam agent chemistry is shared across all oils.

 

[kschachn]

How is 10w40 "VM laden" but not 0w40 or 5w40?

It was a problem with the low-quality VI of the day. Good ones from today are vastly better.

 

[wpod]

May I ask a stupid question? Is a "diesel" oil that has the API service rating SN good for gasoline engines that call for API up to SN rating?

If I may another stupid question - what's the difference with "diesel oil" then?

Diesel oil is what you put in the fue tank, HDEO [ heavy duty engine oil] is what you run in a high speed Diesel engines crankcase.

 

[wpod]

Neither have I as anti-foam agent chemistry is shared across all oils.

Lets talk about the 7.3 Powerstroke engines ability of foam because of their injection system. HDEO oil foaming at gas engines RPMs is a foolish notion.

 

[ARCOgraphite]

How is 10w40 "VM laden" but not 0w40 or 5w40?

The MB 229.5x and Porsche A40 Certs assure high performance with a ACEA HIGH MARGINAL 30 grade lubricant.

API donut - or none - on the 10W40 only assure the most basic requirements are met.

True they are VM laden and I would prefer a high HTHS 30 grade - but the A40 is nicely laden

- Ken

 

[ARCOgraphite]

Or without knowing what the hell they're talking about, in general.

If you are going to put a laughie on my post you better bring it on, kiddo

 

[RooflessVW]

If you are going to put a laughie on my post you better bring it on, kiddo

I laugh at most of your posts, so

 

[Foxtrot08]

Before we get too into foaming and anti foaming. And foaming at the mouths.


This is foamy oil. About the consistency of shaving cream. And it was supposed to be EP 220 industrial gear oil.

So there’s different notions of foaming here. This is a catastrophic level of foam, caused by an additive manufacturing error, that was exacerbated by water.

Light foaming, from HDEOs in PCEO applications is different. Think of small bubbles inside of the oil. Entrained air can actually cause a significant amount of damage and is a worry in every system.

Would I particularly be worried about using an HDEO in a PCEO application because it will generate foam? No, not really. It’s not ideal, but I wouldn’t worry about it. It’s not going to generate foam like the picture. But it does have the capability to generate entrained air, and leave it in the system, because the reasons why I listed previously and the fact PCEO applications don’t have the dwell time that HDEOs do.