Model A Times Article About Not Using Diesel Oil

OL JENNY

OL JENNY

Senior Member
At the recommendation of many on the Barn, I have been using Rotella 15-40 oil in my Model A. A recent article in The Model A Times advocates not using a Diesel Oil. Has that changed the minds of any of you who like me have been using Rotella 15-40?
 
OL JENNY said:
At the recommendation of many on the Barn, I have been using Rotella 15-40 oil in my Model A. A recent article in The Model A Times advocates not using a Diesel Oil. Has that changed the minds of any of you who like me have been using Rotella 15-40?
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No need for Diesel oil! Any detergent oil for gasoline engines will work just fine! I suspect the use of Diesel oil is due to a mistaken fixation on the reduced level of zinc in modern oils (still more zinc than any 1929-31 oil)!
 
I wouldn't use it simply because the detergents and additives are different for that oil from what a gasoline engine uses. Diesel engines develop soot that a gasoline engine does not.

Motor oil for gasoline engines states such, that it is designed for gasoline motors, on the label.

People are in love with the Diesel Rotella because they think somehow the Fed. Govt. left it alone when they ditched ZDDP in SL and older oils. That's like saying in 1975, when lead was taken out of gasoline, 'Well, Shell still has lead so I'll use that." Like everybody else had to conform to No-Lead but one oil company did not.

It has been talked about a lot, that you really don't need Zinc additives in a 4.0:1, low valve spring pressure Model A Ford engine. I've never heard of anyone having any problem using the SM motor oils in a Model A. And I don't think you will.

But, if it makes you sleep better at nite, get some ZDDP additive and dump in the motor along with Rotella.
 
FYI and to add more zinc to the fire.

Here attached is a technical bulletin from the AERA Automotive Engine Rebuider Association on their research on the best oils for rebuilt engines using flat tappet / camshafts and the need for zinc.... Rotella T is one of the 3 suggested oils with sufficient zinc. At least for initial break in....

View attachment Oil wZinc info.pdf
 
"Diesel oils" are formulated for both diesel and gasoline engines.

They are marketed mainly to the diesel engine fleet guys as a diesel oil, but they do also say you can use it in your gasoline engines, so you don't have to stock different oils (mixed fleet).

Here is a copy/paste of a few small excerpts from the Chevron literature. Shell Rotella T is essentially the same:

"Delo® 400 LE 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 CJ-4 service category and
SAE 15W-40 viscosity grade are recommended."


"Delo® 400 LE SAE 15W-40 is approved for:
• API Service Categories CJ-4, CI-4 PLUS, CI-4,
CH-4, SM" <== SM is spark ignition engines

"Zinc, mass % 0.13" . <== that is 1300 ppm, if you think zinc is important

I have not had a chance to read the oil article in the MAT. I requested a copy of it from the publisher back in January but have not heard back.

YMMV.
.
 
I just checked my containers of Rotella and the old Rotella T jugs had a SM rating, but my new containers of Rotella T4 do not have a SM/SN rating. Shucks
 
This is not the first time I've read about not using diesel oils in the Model A engine. I have not read the Model A Times article. There was another article involving much research posted which appeared to have been written by a Model A enthusiast which came to the same conclusion. Unfortunately in that article the problems with diesel motor oil being used were implied and not based on any actual results. I like facts. Has anyone actually had any engine damage that they can show to prove that diesel oil like Rotella 15-40W does harm to Model A engines? I have not seen or read any yet.
 
I have not seen the Model A Times article, but what was their main concerns with using it?

Regards
Bill
 
OL JENNY said:
I just checked my containers of Rotella and the old Rotella T jugs had a SM rating, but my new containers of Rotella T4 do not have a SM/SN rating. Shucks
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The reason the new oil doesn't have the SM/SN rating is because they still have the high zddp content. The government doesn't want high zddp used in cars with cat. converters, because it slightly shortens the life of them.
 
I don't use or recommend diesel oil in my A, only in my diesel pickup. Something to consider, zinc was not in oils when the A was new. The A engine has a steel cam and only 40 lbs. of valve spring pressure. Zinc became important when the OHV V8's came into being. The only V8 not having cam-wear trouble was the Buick, because it had a steel cam. Use modern oil to keep your A engine clean and well-lubricated, better than when they were new.
 
oldforder said:
The reason the new oil doesn't have the SM/SN rating is because they still have the high zddp content. The government doesn't want high zddp used in cars with cat. converters, because it slightly shortens the life of them.
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You are correct. We may see the API SM or SN ratings go away on all these oils, even though there is no fundamental change to the oil itself, just to discourage use in cars/trucks with catalytic converters. I'm sure glad my Model A does not have a cat converter on it to poison!

Right now Chevron and Mobil are still showing SM or SN on their equivalent oil to Shell Rotella T 15W40. But they, too, may bow to the EPA pressure not to label it for gasoline engines. That does not mean you can't use it in a Model A.
 
Search the net for a Hemmings article 10-18-2012 about the zinc/ phoshorous discussion. The article coincides with a study reported by the Porsche Club of America where 356 4 cylinder motors were torn down after testing and found similar less desireable results for the lifters, etc. with reduced ZDDP levels. The zinc rich oils were affecting catalytic convertors and some other parts and hence were gradually modified to suit modern engines.
 
duke36, please don't take this in the wrong manner but Porsche 356 motors are not Model A engines and I would not even try to identify the differences between them so it is a moot point. Also as we all know the Model A Ford does not have a catalytic converter......
 
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