Why use diesel engine oil.

[thumpar]

So lets not turn this into an "oil thread". I know some people use engine oil normally meant for diesel engines in a gasoline engine. What is the thinking behind it? My only guess is because of the constant speeds and high loads. I am not looking for suggestions on brand or weight just wondering why use diesel oil in a gasoline engine.

 

[Bondo]

Ayuh,.... For Me, it's 'cause it comes in 55 gallon drums, or at worst, in 6 gallon cases,....

Rotella T, 15W-40 is a Great oil, I've run in equipment for decades,....
Why Not run it in the fleet of boats too,..?

 

[fuzzybob]

The diesel oils, Rotella T and Dello 400 15w 40 are suppose to have more zddp ( zink) to reduce ware on flat tappet cams and and the rest of the valve train. True or not?? Do your own research....I use Rotella unless I find the Dello cheaper.

 

[Scott Danforth]

the diesel oil still has more zinc which is a real requirement for flat tappets. the higher zinc was also required in my Audi and VW motors with the overhead cams. most of the older oil formulae had higher zinc, however as the engines of today required less and less and the EPA demanded cleaner tail pipe emissions, the oil companies changed the formulae to remove more and more zinc. OK for roller motors, not so great for older flat tappet motors. etc.

So, since my boat and most of my vehicles still require the higher zinc content as well as the heavier blend, Rotella T to the rescue.

 

[Walt T]

Its the additive package that's different. Diesel fuel produces different gasses in the blow by which circulates inside the engine than gas does. If that is relevant I wouldn't know. I use only diesel rated oil in my trucks at work not because I think it's the best stuff but just to cover my butt. The number one job of oil is to carry heat away from the internal moving parts and to suspend contaminates. It's the oil pump that keeps the parts apart. Diesel or gas oil who really cares. Service intervals are far more critical than what type or brand of oil you use. Private aircraft piston engines use ashless dispersant motor oil. Should we use that in cars? Well the reasoning is the ashless dispersant in rotary motor oil helps neutralize and disperse contaminants that build up in the oil during normal use. So therefore the FAA mandates its use. But if we used normal automotive oil in those engines and changed it at regular service intervals we would be getting rid of the contaminants before they caused any harm anyway. My point is take care of your stuff and your stuff will take care of you. Pay for good oil but pay for the recommended oil for your equipment. You can certainly pay more for the diesel stuff but if you service regularly there's no point. I use synthetic in my stuff heck my ol lady uses a synthetic.. uh well nevermind but I feel good using it and like Bondo using recycled oil from old oilfield Detroit Diesels I've never had an oil related problem. But that is a meaningless statement because NOBODY has had an oil related engine failure. Oil will carry away heat and suspend contaminates no matter what. That's what it is designed to do. Different manufacturers want you to buy theirs so they put additives in it or extol the advantages of their oil on the container and hope you buy theirs.

 

[HT32BSX115]

Its the additive package that's different.

Never let it be said that I would shy away from a "good" oil thread!!

Well, it's actually NOT. (completely different, that is....)

Just about ALL the "C" "Diesel" oils, while yes, they have soot "dispersants", also meet/exceed many or all of the "S" (Service, also called "spark") ratings too.

So most oil marketers like Shell, Chev, Valvoline etc will say that "Fleet" users can buy ONE oil for their mixed fleet of diesel and gasoline powered vehicles.

Shell 5W-40 T6 :

SAE Viscosity Grade: 5W-40
API CJ-4, CI-4 PLUS, CI-4, CH-4, SM, SL, SH; ACEA E9; Caterpillar
ECF-3, ECF-2; Cummins CES 20081; DDC 93K218; Ford WSS
M2C171-E; JASO DH-2, MA; Mack EO-O Premium Plus; MB Approval
228.31; Volvo VDS-4

Delo 400 Multigrade SAE 15W-40 is approved for:
• API Service Categories CI-4 PLUS, CI-4, CH-4, SL
• Cummins CES 20078, 20077, 20076, 20071
.
.
.
Chev Delo 15W-40

Delo 400 Multigrade SAE 15W-40 is a mixed fleet
motor oil recommended for naturally aspirated and
turbocharged four-stroke diesel engines and four-
stroke gasoline engines in which the API CI-4 PLUS
category and SAE 15W-40 viscosity grade are
recommended. It is formulated for engines operating
under severe service and a wide range of climatic
conditions.

I'd say that continuous duty marine service is about as "severe" as you could get.......

The only thing missing is an NMMA FC-W rating......which , truth be known, these oils might probably meet if they were tested!

If you want to learn more about specs etc, http://www.oilspecifications.org/ is a great site for info. there's not a lot of opinion there......