1956 Cadillac - first oil change. What should I use?

[carguyblack]

I'm sure I saw this talked about over the years here, but I can't seem to find it. Would someone please advise what oil type and weight I should use in my rebuilt engine in our 1956 Cadillac 365? It is time to get the break-in oil out of it and I want to use what's best for it now. Thanks for bearing with my question!
Chuck

[Mike Josephic CLC #3877]

Use any name brand (API certified) oil of viscosity
10W-30 or 10W-40 and that will serve you well.

No other additives are really necessary.

Mike

[Jon S]

Agreed.

[Carl Fielding]

Well, there is the qualifier again. That one little word. "Best". The "best" oil, the one which just may give your new engine the gift of eternal life, the possibility to be forever young, why THAT oil will be the highest rated, best by test, most synthetic of all synthetic oils. Now, Chuck, will this car be a daily driver ? Or will it rest a spell from time to time ? There is an oil engineered for cars which lay up for varying periods of time. It is a corrosion protection thing. That oil also has the right amount of zinc and phosphorus for the old flat engines like yours. Best you say ? I like that. That is the way I see it, too. Anyway, daily driver? Oh, and you know about the benefits of synthetic grease, too, right ? Lemme know. You did say "best" ?    -  Carl

[Carl Fielding]

Urp. Say, I forgot to ask you what break in oil you used, and for how long.  -  Carl

[Caddy Wizard]

I only use synthetics in a freshly redone old Cadillac engine.  I know some on the forum will howl and insist the conventional motor oil is better for the old engines, but I find just the opposite.  The synthetic oil will reduce friction and the engine will run as well as it can.  It will also stay cleaner inside.  The only downside to synthetic is that it is so darned slippery that some folks find it leaks a little more.  I am meticulous in how I seal up one of these engines and have not had any trouble getting synthetic oil to stay on the inside of the motor.  10W40 synthetic should be fine.  I prefer Mobil1 brand, but that is a personal preference.


Your mileage may vary!

[C Gorgas]

Would a synthetic oil be okay in a 346 engine or stay with oil-oil? I use ZDDP additive when I change engine oil. chet25441

[Lexi]

I have been advised that you are best to purchase oil that has the ZDDP in it from the manufacturer. Two petroleum based oils for old cars, with increased levels of ZDDP, that I use come to mind: CAM OIL, 15W40 (1600 ppm ZDDP),which was specifically formulated for old cars (including flat tappet engines). The other Oil is Valvoline VR1 10W30 Racing oil, (1400 ppm ZDDP). These are both non-synthetic. I believe VR1 also comes in a synthetic blend. Boss Lubricants is the manufacturer of CAM OIL. Boss added a tackifier to protect your engine for those periods when it is sitting and not used. They responded to the Keith Ansell article, "Our Oil is Killing Our cars" by producing Cam Oil. I am not qualified to say whether synthetic oil is best when compared to regular oil, though I know enough to say that the jury is still out on that one. Boss claimed that one manufacturer advised against using a synthetic for at least 5,500 miles after break-in, (for flat tappet engines). See Ansell's article below. Chuck, I am currently beginning an engine rebuild myself and will keep you posted. Clay/Lexi

http://www.rlengines.com/tech/Oil_is_Killing_our_Cars.pdf

[Jon S]

You guys over-analyze and assume a lot. Dino oil is just fine for our older cars if changed at the recommended intervals. ZDDP additives mix extremely well in an operating engine. Like mixing chocolate syrup in milk. Are synthetic oils better - maybe for today's hotter running emissions laden cars- over-kill for 1950's cars.   JMHO

[Lexi]

I am inclined to agree with Jon and still use "Dinosaur Juice" in my 365. Regular oil changes are very important to keep your engine internals clean. Clay/Lexi

[David King (kz78hy)]

I point and click.  The case shows up on my door step.  Plenty of zinc and designed for low use.  You can read the propaganda on the page if you like, but good stuff.

https://classiccarmotoroil.com

David

[carguyblack]

Thanks everyone for your advice and suggestions. You are all very helpful and informative!
One thing you didn't answer was: Can I run my car 2 quarts low to save money?
(That was just a poor joke. Sorry!)
Chuck

[Lexi]

That was not a poor joke, that was an example of classic Chuck humor (as we discussed in June)...!!! Clay/Lexi