'56 Coupe Deville, engine oil

[Wacco65]

'56 Coupe De ville, I've just rebuilt the 365, i was wondering what is the correct engine oil grade. e.g 20w20 ; 20w30 ; 20w40?

[J. Gomez]

'56 Coupe De ville, I've just rebuilt the 365, i was wondering what is the correct engine oil grade. e.g 20w20 ; 20w30 ; 20w40?

Wayne,

Are you looking for the “brake in” or conventional oil type after the rebuild?   

If you have the Service Manual check Section 2 Fig 2-5 should show you the suggested oil viscosity for conventional oil but 10W-30 should be adequate for normal range.   

Good luck..!

[Caddy Wizard]

10w40 would be my choice for all around use.  If your summers are especially hot, you could run 20w50 in the summer if your oil pressure dips low when the engine gets hot (and the 56 engine runs hotter than most years due to the high compression and small radiator capacity). 


Some folks don't like synthetic oil, but I do prefer it myself with a newly rebuilt motor.  If you don't like synthetic, consider an oil that contains ZDDP.  If you can't find an oil with about 1000 ppm of ZDDP in it, you could always add the ZDDP.  There is a company in Indiana selling a 10w40 conventional motor oil with 1600 ppm of ZDDP in it. https://classiccarmotoroil.com/properties.html

[Dan LeBlanc]

Shell Rotella 15W-40 is the way I go.  Contains way more than enough ZDDP.  A 5qt jug is under $25 and is available just about anywhere.

[James Landi]

Hi Wayne,

There's plenty of good advice here... I'll just add in a word of caution that may receive some additional conversation.   I owned two '56 sedans during the 60's and up until 1980.  For many reasons that are not clear to me, the engine oil pan tends to develop sludge.  If memory serves, taking down the oil pan is not a huge operation, so cleaning out the lower end is not a bad plan.   Another word of caution, as you know, you have a oil light instead of a gauge.  Engines of this period do no produce much oil pressure at idle, and when hot (and the '56 is notoriously hot), the oil light will blink...so an oil gauge on this engine tends to make modern owners crazy---  while you might be attached to single grade oil, say heavy service 30, you may be far better off with a multi grade that provides lubrication when the engine is cold, or when you're using the car for short runs.  A single grade oil will cause an accessory oil gauge to stay at a higher pressure, but will likely starve lubrication when you need it for short runs.  As far as the zinc goes, there's a bunch of good advice here, as well as Google searches -- I suggest, by way of summarizing my comments as follows:  How are you going to use this car?  Long extended summer runs?  Do you have a tendency to use passing gear, and push the engine to high rpms, or will this car be used for occasional, light use.  Makes a difference.  Happy day,   James

[Caddy Wizard]

Shell Rotella 15W-40 is the way I go.  Contains way more than enough ZDDP.  A 5qt jug is under $25 and is available just about anywhere.

The Rotella is a good option.  I like that one...

[BJM]

I would say go with Rotella 15W-40 for conventional oil as well.  A few considerations are the amount of driving you might do.  As a collector car, I don't drive any of mine more than 3000 miles a year. 

Modern oils are so much better quality than 1956 options. Not sure sludge will become an issue, especially with annual changes. 

[James Landi]

Sludge---Bryan, I think the major challenge is the inevitable condensation that occurs with pre-mid-60's cars that don't have a simple PVC device.   Temperature differential between the top end of the engine and the oil pan, the tendency for moisture to turn to "drips of water" and then to mix with the oil in the crank case, and the cycles of heating and cooling. I don't think contemporary oils have that level of moisture concern as a challenge to overcome.  Both of my 56 SDV's had sludge in the oil pan, and they were daily drivers-- one was my commuter car-- 90 miles a day...went through a set of rings and replaced bearings shortly after attaining 120K miles.     Especially a concern for "garage queens" that often don't get up to temperature.  Happy day,  James

[35-709]

Believe it or not WalMart's Super-Tech 15W-40 oil is highly rated and contains appox. 1237ppm of Zinc.

http://www.pqiamerica.com/May%202013/supertech.htm

You can just click cancel on the Adobe Flashplayer pop-up.

[35-709]

Next question might be, "Who makes Super-Tech?"

From "Bob-is-the-oil-guy" forums ---
"The oil is formulated and blended by Warren Performance Products or WPP, a third party blender/bottler/labeler.  "Warren Oil and WPP are two different companies according to my info."

Again from the Bob-is, etc., etc. forums, concerning it's lower price ---

"The only problem with SuperTech motor oil is that WalMart doesn't promote "image" by packaging it in macho designer bottles with hex-head caps, scent the product with extract of fruity candy, or spend lavishly on TV ads touting their motor oils' use at Le Mans, Indianopolis, the Pike's Peak Hill Climb, the annual Soap Box Derby, and as original factory lube for Schuco clockwork car repros, Cracker Jacks clicker toys, etc."   

[Lexi]

CAM OIL, 15W40 (1600 ppm ZDDP) by Boss Lubricants, specifically formulated for old cars and Valvoline VR1 10W30 racing oil, (1400 ppm ZDDP). These are both non-synthetic. I believe the VR1 also comes in a synthetic blend. Another high zinc product, 20W50 racing oil by Kendall, non-synthetic. I use the Kendall to top up during the summer, though I might consider using it alone, during hot driving conditions in a high mileage engine. Clay/Lexi

[carguyblack]

I've been reading old posts about engine oil preferences and am curious about the Supertech 15-40 mentioned from Walmart. I recently went there to take a look and the only oil offered by them is a Deisel Heavy Duty oil version in that weight. My question is: Can one use diesel specified oil in a conventional engine, such as our 1956-365?
Thanks!
Chuck

[Dave Shepherd]

Latest info around, by knowledgeable  people is diesel oil is not recommended  for gasoline engines, based on additive package not designed for that use. There have been several articles in automotive publications relating  to this topic.

[carguyblack]

Thanks, Dave. I was uneasy about it and you confirmed.

[TJ Hopland]

Latest info around, by knowledgeable  people is diesel oil is not recommended  for gasoline engines, based on additive package not designed for that use. There have been several articles in automotive publications relating  to this topic.

Any links to this new information? A long time ago I was skeptical that it was a good idea but what changed my mind was seeing that most diesel oils in addition to their API C(compression/diesel) rating also carry an API S(spark/gas) rating.

I'm not saying diesel oils are some amazing thing and everyone should go with them but like most other options out there I don't think they are bad. Pretty much any modern oil is going to be better than what was around when these engines were new and most of the time we are not using these cars that hard so we are not putting a lot of stress on the oil.

Even modern diesels by their high compression nature end up with a lot of contamination that gets past the rings and gets in the oil. Diesel oils have extra additives to deal with this contamination.  What are 'old' either due to mileage or the era they were designed in also known for?  Stuff getting past the rings into the oil?  Less effective crankcase ventilation? 

The biggest reason I have been using diesel oils in my fleet is I have diesels and I don't like having to 'stock' a dozen different oils. I buy 5w-40 in 5 gallon buckets and use it in all my small engines and cars except for my still under warranty VW which happens to be a diesel but that calls for a fancy euro spec 0w-20. I also care for a newer GM truck that wants a Dexos also 0w-20 I think but everything else which is at least 20 years old gets the diesel stuff.

Now most people don't own any diesels and maybe don't have the volume of engines needing oil that people like me do so finding one oil for most everything isn't a factor but even if I got rid of my diesels I think at this point I would stick with with it.   The 5w-40 is just a good range for me that lives in a climate that sees -0*F as well as +100*F temp ranges. 

To get the 5w-40 range you do need to go to a blend or full synthetic but I think its worth it if you live in a climate that sees freezing temps. Many of my engines are not used that often so changing the oil twice a year to get both a summer and winter oil is just a big waste and stuff happens and plans change so there are times something has to get started in its off season so its nice that having the wrong season oil in it isn't an issue.

Like I said I'm not saying my choice is better than others, I'm just saying why I made the choice I did. For the older and small air cooled engines (that also tend to be older) I like the idea that the diesel oils are made for engines that are likely to get a lot of contamination in the oil.                             

[Jon S]

I add 8 ounces of Red line's Break In oil every oil change with a high-quality non-synthetic 10W/30 or 10W/40. This provides more than sufficient, zinc and phosphorus. I would suggest it is for your 1956.

[Dave Shepherd]

Any links to this new information? A long time ago I was skeptical that it was a good idea but what changed my mind was seeing that most diesel oils in addition to their API C(compression/diesel) rating also carry an API S(spark/gas) rating.

I'm not saying diesel oils are some amazing thing and everyone should go with them but like most other options out there I don't think they are bad. Pretty much any modern oil is going to be better than what was around when these engines were new and most of the time we are not using these cars that hard so we are not putting a lot of stress on the oil.

Even modern diesels by their high compression nature end up with a lot of contamination that gets past the rings and gets in the oil. Diesel oils have extra additives to deal with this contamination.  What are 'old' either due to mileage or the era they were designed in also known for?  Stuff getting past the rings into the oil?  Less effective crankcase ventilation? 

The biggest reason I have been using diesel oils in my fleet is I have diesels and I don't like having to 'stock' a dozen different oils. I buy 5w-40 in 5 gallon buckets and use it in all my small engines and cars except for my still under warranty VW which happens to be a diesel but that calls for a fancy euro spec 0w-20. I also care for a newer GM truck that wants a Dexos also 0w-20 I think but everything else which is at least 20 years old gets the diesel stuff.

Now most people don't own any diesels and maybe don't have the volume of engines needing oil that people like me do so finding one oil for most everything isn't a factor but even if I got rid of my diesels I think at this point I would stick with with it.   The 5w-40 is just a good range for me that lives in a climate that sees -0*F as well as +100*F temp ranges. 

To get the 5w-40 range you do need to go to a blend or full synthetic but I think its worth it if you live in a climate that sees freezing temps. Many of my engines are not used that often so changing the oil twice a year to get both a summer and winter oil is just a big waste and stuff happens and plans change so there are times something has to get started in its off season so its nice that having the wrong season oil in it isn't an issue.

Like I said I'm not saying my choice is better than others, I'm just saying why I made the choice I did. For the older and small air cooled engines (that also tend to be older) I like the idea that the diesel oils are made for engines that are likely to get a lot of contamination in the oil.                             

https://www.speedwaymotors.com/the-toolbox/diesel-oil-in-gas-engine-will-it-hurt-my-engine/53662. Here's one, but I read a really comprehensive article  in a trade mag.

[TJ Hopland]

That article was a lot of reading that barely said anything. And I'm still not saying I'm right here or that anyone should do what I do but I would like to understand why it may not be good and I don't think this article really explained anything unless someone can explain or expand on the bits below...

What the heck are they talking about here?   
"diesel oil has so much more detergent. It can remove factory-applied coatings on internal components that are meant to seal the engine's combustion gases"

Are they talking about coated rings? If so there are coatings that can stand up to combustion and friction but detergent in oil can destroy it?
 

And then they go on to say that after these coatings have been removed the increased oil consumption could long term damage your cat?  But if you don't have a cat then no problem?


And I'm not talking about Zinc, that a whole other thing in itself.  If Zinc is your goal you have to buy additives or go out of your way to get a special oil. 

[Dave Shepherd]

Agreed on the article, but I read one from a chemical engineer that was more comprehensive, was in a trade magazine, but I couldn't find it. Also read that zddp additives do not blend with the oil at a molecular level, that it must be  introduced during the refining  of the product. Again, this is an "I read" issue.