Diesel oil in Gas engine?

[imoldernu]

Here's the situation:

Went into Rural King (like Tractor Supply), and found a 2 gallon synthetic Motor Oil... 5W 30... SM SN rating. It was manufactured by Warren Oil. Later, I went online, and found the 1 quart container, but posted in the Tractor/Equipment category. The container label only says "Motor Oil".

The price was definitely right... $17.97, less a 10% sale price... That comes to @2.02/qt. That was a few weeks ago. I changed my oil, and was pleased with the price... much cheaper than Mobil 1 @ $6/qt. (my car takes 8 quarts).

Hmmm... yeah, pleased with the price until the guy next door (who was a farmer) says to me... "Whaaat? You put Diesel engine oil into a Gas engine. Good Luck!"

Well, nothing on the container said "Diesel"... and it did have an SN-SM rating. So far, so good... but... am I waiting on a problem?

 

[rbmrtn]

The additive mix may be different, but may not harm anything. Lot of people use Rotella

Here's a thread from Bob is the oil guy site ( search there for more ). Lot gearheads there

diesel motor oil in a gas engine | Passenger Car Motor Oil (PCMO) - Diesel Cars/Vans/SUVs | Bob Is The Oil Guy

Another from Cartalk

Use of diesel oil in gas engines - Good idea or not? - Car Talk

 

[bld999]

Diesel engine oils have api designations such as "CL-4" with gasoline intended oils using the "S" series SL being the current one. If an oil is rated both C and S, and as long as the viscosity is correct, there should not be a problem.

Some Heavy duty oils have a lot of zddp in them which can cause problems with cat converters if the engine is burning oil. You would not come by that info unless you had an analysis done in most cases.

 

[calmloki]

Have run diesel rated oil in my 2000 BMW 6 during my ownership from 250k to 310k miles. No ill effects. Before coming north on a 1100 mile drive I changed to full synthetic Mobile 1 gas engine oil (Walmart 5 Q jugs - $27). Also switched from premium to regular gas, and it has given equal or better economy and power for $0.20 less per gallon - and not a hint of pinging. That change is over the last 3500 miles.

 

[imoldernu]

Thanks for the quick replies.
I'm interested in the rating system, and found this site, that explains all of the oil ratings... especially the American Petroleum Institute "donut" label that shows the different parts of the rating... ie. The SN rating being the latest, for the newest cars.
The other part that is interesting is that the "W" part of the rating, as in 5W30... and the difference between that and a 5-30 rating... ie. SAE 5W30 is not the same as SAE 5-30.

API Engine Oil Classification

 

[aja8888]

I run CJ-4 oil in my Jetta Turbocharged diesel. The diesel rated oils are formulated to neutralize H2SO4 (sulfuric acid) which forms as a result of sulfur laden diesel fuel. This is not much of an issue now that diesel fuel for road use is <15 PPM sulfur. Prior to 2010 or so, it could have been as high as 500 PPM.

In older (pre 2008 or so) gasoline engine cars that have no issue with ash forming from burning some oil the motor oil and crapping up the converter or other pollution control devices, running the older CJ-4 spec oil is no problem. CJ-4 is virtually not found anymore unless you run across Shell Rotella T in a blue 5W 40 jug.

As long as the API spec for your car is on the oil jug and the weight range is correct, you should have no problems with your Cadillac. In hot climates it's OK to run a more viscous oil say 10W 40 vs 5W 30.

 

[38Chevy454]

Diesel oil has different additive package as stated. Diesel oils are great for older carbed engines and even some early fuel injected engines. All diesel oils are typically called heavy duty engine oil, but the real indicator is the service rating. Diesel oil is actually really good oil for severe engine condition use, even in gasoline engines. The small amount of the additives that could mess up the catalytic converter is only an issue if your engine burns oil.

Your SM/SN oil is regular passenger car type oil. Use it and don't worry.

 

[Koolau]

Heh, heh, years ago, I had a beater which used so much oil I began putting some left-over transmission fluid in it when it was a quart low (about every 200 miles). Seemed to work fine, but, then again, I wasn't too worried about the engine going bad (too late to worry about that!) Nor did it have a Cat Converter. Just a POS that got me from point A - B on an occasional basis. I gifted the vehicle eventually and it ran for quite some time after that. YMMV, so to speak.

 

[marko]

Not sure it is so today, but back in the day, there were oils rated as "SD" (severe diesel) which was supposed to be the best thing you could put in a hard working gas engine because if it was good for a diesel under stress it would be just fine for you beater.

 

[NW-Bound]

I have always thought that engine oil for demanding diesel engines is safe for gasoline engines, and it looks like I am right. Still, this thread reminds me that I never think of looking up the rating of the oil I buy, as I assume that stores only sell the latest stuff.

So, I run out to my garage to check on all the different cans I have. All are rated SN or SM, and often in such small letters hard to find. Can one really get something else?

 

[rbmrtn]

So, I run out to my garage to check on all the different cans I have. All are rated SN or SM, and often in such small letters hard to find. Can one really get something else?

Yep, take a look at this site. They buy oil of the shelf and test it. Lot of off brand stuff at the mini-marts is suspect.

The Petroleum Quality Institute of America

 

[NW-Bound]

Interesting. I do not buy oil in mini-marts, but do not recall seeing these off-brands here. I usually buy what's on sale at AutoZone, O'Reilly, and Walmart, and they carry only brand names.

 

[NW-Bound]

And speaking of Walmart, what do you think of their brand of synthetics, Super Tech?

On the Web, people say that Shell makes it for Walmart. As I tend to change oil early, meaning usually 3-4K mi for regular oil, and 7-8K for synthetics, I do not worry too much about the possibility of an oil not being premium (mini-mart oil described above excepted).

What do you think?

 

[springnr]

For those who find such interesting, decent tutorial:
Motor Oil 101 - Bob is the Oil Guy - Bob is the Oil Guy

 

[rbmrtn]

And speaking of Walmart, what do you think of their brand of synthetics, Super Tech?

On the Web, people say that Shell makes it for Walmart. As I tend to change oil early, meaning usually 3-4K mi for regular oil, and 7-8K for synthetics, I do not worry too much about the possibility of an oil not being premium (mini-mart oil described above excepted).

What do you think?

any Motor oil as long as it meets the API should be ok. The additive mix is what makes one a better than others. Supertech usually gets good marks

BITOG

Walmart SuperTech Synthetic spec sheet info | Virgin Oil Analysis - PCMO/HDEO | Bob Is The Oil Guy

PQIA
Petroleum Quality Institute of America

I tend to buy what is on sale and stockpile. I bought about 150 qts of nextgen for about 50 cents each last year at Oriellys when it was on clearance and had a coupon.