diesel oil in a gas engine?

[Robbie Alexander]

quote:

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Originally posted by iskerbibel:
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BTW, before I started working as a heavy equipment mechanic(with access to free oil), I used to run either Coastal or Advance Auto Parts oil in most everything... or sometimes super-tech- I've never seen any apparent difference- if it says API SL, oil is oil, right?

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Nope.
Think of it this way... you can have access to the same tools to build a house or bake a cake, and have two or three or whatever number you decide, contractors build the house/cake (oil),
but no two are going to do the exact same results, even if following a Blue Print...
Someone will have that extra little touch or finish to make what they created better. Besides, I know that the OIL mfgrs. do no use or buy the supplies for their brews from the same people. It's a big market out there and someone is always gonna cut this corner or that one and no two cut the same.

 

[badnews]

quote:

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BTW, before I started working as a heavy equipment mechanic(with access to free oil), I used to run either Coastal or Advance Auto Parts oil in most everything... or sometimes super-tech- I've never seen any apparent difference- if it says API SL, oil is oil, right

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For the majority of applications, yes . Special applications may demand a special brew.

[ September 22, 2003, 07:37 AM: Message edited by: badnews ]

 

[widman]

No problem running the "fleet oils" in gasoline engines. A little extra protection.
-Userfriendly: I wouldn't think of using straight wt oil when temperatures are below 20 to 25 C, even if it is 30wt. CAT, without having to comply with CAFE specifically recommends against it.

 

[TC]

I had the same question as Iskerbibel. After reading through this, I wanted to make sure I got my conclusions straight -- please correct me if I'm wrong. In the most concise of layman's terms:

1. "Diesel" oils are perfectly safe for gasoline burners if "SL" rated.
2. Diesel oils will keep lubed components cleaner due to increased "ash type" detergents.
3. ...But these additional additives MAY cause increased combustion chamber deposits.
4. So you're better off NOT using diesel oil in a gasoline burner.
5. ...UNLESS you have a need for advanced cleaning capability such as if you notice increasing sludge, varnish, etc. when viewing valvetrain through the oil filler cap hole (or through oil analysis).

Does this provide an accurate short version of the thread? If so, I'll walk away from the diesel lubes -- I had been eyeing them lately for my petrol slurper.

By the way, "Userfriendly": The dancing puff ball icon is a marshmallow on LSD.

 

[Jelly]

"1. "Diesel" oils are perfectly safe for gasoline burners if "SL" rated."

Well, "mixed-fleet" oils are perfectly safe, and they don't have to be SL rated as long as your vehicle doesn't call for a SL rating in the manual (reason being new cataylic converters are supposedly more sensitive to phosphorus.)

"2. Diesel oils will keep lubed components cleaner due to increased "ash type" detergents."

Detergents and dispersants...compared to a PAO or ester-based synthetic, I really don't think so, but compared to all mineral-based oils...yes.

"3. ...But these additional additives MAY cause increased combustion chamber deposits."

Yes, higher sulfated ash will cause higher deposits, and while CI-4/SL HDEO's are currently around 1.3% ash content, synthetics are very close, around 1.2%...I wouldn't worry about it unless you burn a high amount of oil...then I wouldn't use either.

"4. So you're better off NOT using diesel oil in a gasoline burner.
5. ...UNLESS you have a need for advanced cleaning capability such as if you notice increasing sludge, varnish, etc. when viewing valvetrain through the oil filler cap hole."

Well, yes and no. I use HDEO's because of a few things...great protection (Anti-wear, extreme pressure, and keeping engine clean), extended drain intervals (mineral base, but high TBN and high additive levels), and low price ($6/gallon vs. $4 quart for synthetics)

"Does this provide an accurate short version of the thread? If so, I'll walk away from the diesel lubes -- I had been eyeing them lately for my petrol slurper."

No need to walk away from a mixed-fleet lube as long as it's viscosity meets your requirements. You get a great oil for a low price. If you don't mind paying a little more though, then go with a true synthetic...better low and high temperature performance.

 

[TC]

Very interesting, and very helpful, "Jelly." I was especially intrigued by your comment that sulfated ash levels in diesel oils were very similar to synthetic oils. Yet nobody who's using syn is moaning about combustion chamber deposits, so why should this be a unique concern for diesel oil users?

I picked a random brand -- Chevron -- and got some numbers off their website. I know that anti-wear additive zinc can also cause combustion deposits, and anti-wear phosphorus can eventually "poison" a catalytic converter, so I included them as well. The three oils are Chevron Supreme (conventional), Chevron 100% Synthetic, and Chevron Delo 400 (diesel/gas), all three oils being 10w-30.

-Supreme: Sulf Ash 0.90%, Zinc 0.103%, Phos 0.094%
-Syn: Sulf Ash 1.11%, Zinc 0.128%, Phos 0.092%
-Delo: Sulf Ash 1.34%, Zinc 0.140%, Phos 1.26%

Looks like there's significant, although not dramatic, differences in these additive concentrations. Food for thought. But I have two last questions to pose:

1. As a formality, I should ensure that the additives don't care what the carrier is: Two identical engines operated in similar fashion, one lubed with conventional, the other with synthetic, both oils containing the same level of ash, will likely have the same level of combustion deposits. True/False

2. If one is concerned about "diesel oil" deposits in a gasoline burner, simply find a diesel oil brand that has comparatively low levels of ash/zinc/phosphorus. Sound logical?

Thanks!!!

 

[Ken2]

Not that simple.

1) Not all sulphated ash is equal. The ash mainly comes from the metalic salts used as detergents. If a magnesium compound is used, the ash tends to be abrasive and can build up in ring grooves as well as abrade or polish cylinder walls. If calcium compounds are used, the ash is softer, much less abrasive, and can dissolve in oil instead of forming deposits.

2) Buy an SL rated oil and don't worry. Pick an oil based on total performance, not one or two aspects of the oil.


Ken

[ October 01, 2003, 11:12 PM: Message edited by: Ken2 ]

 

[Jimbo]

Ash levels correlate more closely with TBN than EP/AW additive levels. The latest formulas use calcium as the primary buffer salt, just like "Tums".

 

[rpn453]

quote:

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Originally posted by Doug Hillary:
No excess of air occurs at all - you must be living in the Detroit 2 cycle era

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I'm confused. You mean for a given rpm in a newer diesel the air flow into the engine is no longer constant (at constant boost level)? So they now have throttles? Apparently I need some updating.

 

[Doug Hillary]

Hi,
the comment "diesels run an excess of air" in the context offered I believe applied to Detroit and other 2 cycle engines. These engines had a need to scavange the burnt fuel mixture and this was primarily done in Detroits by "air pumping" via a Roots type supercharger - "excess air" supplied then at about twice the actual need for combustion. The "Jimmy" had/has a great sound for this reason

The modern diesel engine has electronic fuel/air management controls that enables precise combustion mixture mangement. On overrun and when using a compression brake, only air is used

Regards

 

[TC]

Thanks for all your great feedback here, Jelly and Ken2. It has helped put all this in perspective .

I'll retract my earlier comment that ash content didn't appear to vary dramatically between blends. In fact, Shell and Pennzoil "diesel/gasoline" oils have about 83% more sulfated ash than Valvoline and Union 76 "gasoline" oils (the 10w-30 numbers are 1.47%, 1.45%, 0.80%, and 0.80%, respectively). So that's not only a dramatic difference, but is close to DOUBLE the concentration. I'm sure the added detergents/dispersants are of great help in "heavy duty" and "severe service" gasoline applications, and certainly for any extended service drains. But rightly or wrongly I suspect that diesel oils would pose an unnecessary risk -- even if only a subtle risk -- of combustion deposits for my 2002 Mopar gas burner (and I'm using my car as a surrogate for others in my situation as well). I say "unnecessary" in that the gasoline oil I've been using shows no hint of sludge or varnish buildup, so I don't readily see any need for additional D/Ds, especially if there's a modest, potential trade-off (combustion deposits) in doing so. But everyone's situation is unique, and I'm sure there's more than a few gas burners out there that could benefit from diesel oils' additional D/Ds for varied reasons.

For what it's worth, I should mention that of the three diesel oils I looked into, only Chevron trumpets a "low ash" formula, although in fact they contain only about 8% less than Shell and Pennzoil.

 

[GregH]

Ken2, I noticed you mentioned magnesium as a source of abrasive deposits. How does Mobil get by using what I would think is a lot in Delvac 1300 and Delvac 1 and show good wear. I s this a long term issue. I think that you and Bob mentioned the same issue but haven't heard others mention it . Is there something I am missing. Just curious as usual!
gregH

 

[iskerbibel]

Just to clear something up:

About excess air in diesel engine combustion- no, the is still no throttle body of any sort on a diesel engine, including the modern computer-controlled engines. In any condition other than full load, the engine is taking in much more air than is neccesary to burn the amount of fuel that is being injected. I've driven and worked on quite a number of diesel engines, and if I saw the pyrometer going anywhere near 1500 degrees, I'd be shocked and concerned. Even on engines where some idiot has "turned up the fuel", I've rarely seen anything over 1150.

 

[Bio-T]

On my truck I have the pyro in the exhaust manifold pre-turbo and I can get to 1400 plus with a chip and 22-24 pounds of boost. I also have a pyro after the turbo where most HD diesel engines are mounted and I do see as much as 300 degrees lower under the same conditions. So pyro mounting is important.
I use the pre-turbo pyro for running/towing, and the after turbo pyro for shut down as the exhaust will cool faster than the turbo after a hard pull/towing.

 

[iskerbibel]

hmmm... I stand somewhat corrected- what engine is this? what chip?

 

[Doug Hillary]

Hi,
TC - the ash content of the oil is sometimes specified by the engine makers

Some significant differences exist between Euro, Japanese and American makers in this regard. It has a lot to do with the combustion process including combustion chamber design, ring position, piston design and a plethora of other such design issues. Many if not most are emissions driven
With a modern diesel engine it is extremely important to adhere to the maker's recommended oil specification. In recent years these have become more specific to engine "family" and model

When running a "fleet" oil in a petrol engine the API's "S" rating says it all. The better fleet oils today are as you know CI/SL rated

In many applications these "fleet" oils can be used in cars, fork trucks ( petrol/diesel),light trucks ( petrol/diesel) loaders, reefer units, heavy trucks etc. etc.

Regards

 

[Robbie Alexander]

quote:

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Originally posted by Doug Hillary:
*-*-*-*-*-*
In many applications these "fleet" oils can be used in cars, fork trucks ( petrol/diesel),light trucks ( petrol/diesel) loaders, reefer units, heavy trucks etc. etc.

Regards

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True, and I do use a fleet oil myself, BUT:
It is DESIGNED chiefly for the BIG RIG, for the DOZER amd Tractor and such. Yes Sir, it (some new ones)does meet the SL spec's but for the most part, most are not designed and tested for Millions of K's or Hours or whatever in the "GAS or other" engines, that is just an after result.
My experience though with many oils is in general, they do tend to hold up better and give better gas milage for my applications (usually small 4-bangers Rid-Hard and Put-away-wet). Most of my applications were Courier or Outside-Sales.

 

[TC]

Thanks, Doug.

There's a few diesel/gasoline oils out there marketed as "low ash" products. Perhaps some of you diesel gurus can offer some insight into the pros/cons of these oils in either gas or diesel burners. For that matter, if they're reducing "ash type" detergents/dispersants/etc., what specific "low ash/no ash" compounds are they replacing them with? And what might these show up as through a VOA/UOA?

Two examples of gas/diesel oils marketed as "low ash" include:

Chevron Delo 400
10w-30 ash content of 1.34%
From their spec sheet: "Minimum combustion chamber and valve face deposits are the result of low sulfated ash levels in the oil."

Citgo Transit
15w-40 ash content 0.9%
"Excellent detergent control of piston ring deposits in highly stressed engines."

In comparison, other ash rates include Shell Rotella 15w-40 (1.47%), Pennzoil Long Life 15w-40 (1.45%), Kendall GT-1 10w-40 (gas only, 0.80%), and Texaco Havoline 10w-40 (gas only, 0.90%).

Thanks for any feedback as to "low ash diesel" pros/cons!

[ October 14, 2003, 04:35 PM: Message edited by: TC ]

 

[Doug Hillary]

Hi,
TC - if you are using a "fleet" oil in petrol engines it is assumed that you would be changing the oil at or close to the recommended intervals. The ash content is therefore irrelevant because of the oils joint API rating -say CI/SL

Ash levels are critical in diesels due to their induction system design, specific/individual combustion chamber design/process, top ring position and valves. Excessive ash deposits seriously affect performance in this area

The levels vary greatly with American, Euro and Japanese design differences

In oil specs., 2 cycle Detroits require a Max of 1% and 4 cycle Detroits ( DDEC 2-4 ) require a Max of 2%

Regards