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65 deville 429 - which oil after break-in oil

Started by johngmm7, July 20, 2020, 06:33:47 PM

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johngmm7

My 65 deville has covered about 250 miles since changing from break-in oil after 2 to 300 miles. I replaced the filter and refilled the sump with Chevron 5-30.  The guy who did the rebuild scalded me for this and stated I may have damaged the new crankshaft as I should have refilled with zinc oil.  He said the pistons and valves would not be affected.  He insists he told me to change to zinc oil after the break-in period.  I have just searched on line for verification and cannot find any definite proof of what he has told me. I also thought of using synthetic until I heard this  So I am now uncertain as to which is correct.
Any and all comments will be greatly appreciated.  Thanks, John

savemy67

Hello John,

ZDDP (zinc dialkyl dithiophosphate) is an additive developed for use in some of the toughest internal combustion engine environments - airplanes.  It was found to be quite useful in automobile engines to reduce wear in locations where metal to metal contact was quite extreme, such as where the camshaft lobes contact the bottom of the lifters.

Our old engines are known as flat-tappet engines.  A lot of force is generated when the cam lobes overcome the resistance of the valve springs.  Valve springs are quite strong as they have to withstand the dynamic forces associated with opening and closing valves.  Some race engines use two springs per valve, one inside the other, because the dynamic forces are very pronounced.

Today's engines on the other hand are all about maximizing fuel economy, so most lifters in today's engines are equipped with rollers at the bottom of the lifter.  The roller greatly reduces the wear as the cam lobe pushes the lifter to open the valve.  As such, there is less need for the type of protection offered by ZDDP.

You can search on-line for several name brand motor oils that offer oil with ZDDP.  There is probably a point of diminishing returns, so spending $25 per quart of oil with copious amounts of ZDDP is probably not worth it.

I would suggest you consider using 10W-30 as I don't think it gets cold enough in your neck of the woods to warrant the use of 5W-30.

I am sure others will chime in, any moment now...

Respectfully submitted,

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Lexi

#2
I hesitate to respond, as I cannot answer your question with much certainty from this vantage point at my PC. I can only relate to my experience. After my rebuild the shop filled the engine with a break in oil and ran it as per their break in regimen for about 40 minutes at a specific (or various) RPMs. Cam was mostly set after this, I was told. Immediately after this that oil was changed with the "dinosaur juice" oil I provided. It had a high zinc content. I was then told to drive the car like "I stole it", mixed with more moderate speeds (but with little or no idling) for at least the first 1,000 - 2,000 miles. I changed that oil again 100 miles later. I noticed some marbleized swirl in the used oil which I took to be remnants left over from the re-build. There was also some fine particulate matter noted, that looked like fine pepper grains. Shop inspected, and advised that some of that is normal after a rebuild, especially if not all the crud was thoroughly cleaned out. Most of that should clear up in a few oil changes and that no large particles were showing, or should show.

Opinions are all over about how to break in an engine and what oil to use. I do know that a machine shop owner advised that they routinely test the oil of rebuilds and that an abnormal quantity of trace metal can still be found in some cases up to 10,000 miles later. Unless your engine is experiencing odd mechanical symptoms, (such as making certain unusual noises, knocking, low oil pressure, for example), I would not hit the panic button. I would change the oil asap and replace with a high zinc content oil; then change it frequently at least for the first 2,000 - 3,000 miles.

Right now changing your oil (and filter), a lot, is for 2 reasons; 1) Get rid of the crud and particulate matter left over from the rebuild 2) Continue to assist in the breakin process which I am told is ongoing for a while. How long I am not sure. No one seems to agree on this. I was told however, that for some time after the various parts will continue to wear as they continue to mesh together when the engine is operational. Whether or not you damaged your crankshaft is hard to say, but again if no odd noises, or drop in oil pressure, just go to plan B and use dinosaur juice. Stick with regular high zinc oil instead of synthetic until at least 2,000 - 3,000 miles the machine shop told me. Then go to high zinc synthetic if you wish. As you change your oil watch its appearance. You may even wish to cut open the filter and have a look at what is being trapped. If you have an engine that is slowly eating itself up I imagine there will be traces of this found in your oil and/or in the oil filter. You may also want to install a magnetic oil drain plug for a while. So do frequent oil changes and be mindful of odd engine noises.

My guess is that you probably are OK, but should be keying on the above to ensure the best possible breakin. Regardless, keep an eye (and ear) alerted for issues and begin using high zinc oil immediately. I agree with Chris that 10W30 is fine. I currently use Valvoline VR1 racing oil (not synthetic). Although a racing oil it is said to be formulated also for use in old cars. There are several brands to choose from. Also, if you properly break in your engine your vacuum should increase. Mine went up about 1 3/4 inches. That I believe is more a sign of the rings setting properly, but is also a good indicator that you are doing things right. I change my oil usually every 500 - 700 miles, but did so more after the rebuild, (every 100 - 250 miles). Hopefully someone with more experience can jump in if I have made errors here. Clay/Lexi

TJ Hopland

For break in I would always go with what the builder says no matter what the cost is.  If you are the builder then I would look for recommendations from the cam and lifter people.  If they say to use super duper brand x racing oil with 10% magic mix 5 million additive which they happen to sell that is what I would do.   

After that I would ask what they think would be a good one but trust them a little less if its still an expensive oil they sell.  The answer I like to hear is to have them ask what brands I like or say any big brand name 5w or 10w whatever.   There may be a specific brand they say they don't like but when they say there is one brand that is the 'best' I start to wonder especially when they sell it.

Diesel oils are worth considering.  Its not just weirdos like me that think its OK, the American Petroleum Institute actually tests and certifies many of them for use in gas engines.   If you look at the API labels they give a C and S ratings.   C is for compression which is diesels.  S is for spark which is gas.    The S ratings usually lag a letter or two behind the most common current gas rating so they usually still have more of the good toxic stuff in them and you would not want to use them in a newer gas engine.    Synthetic blends are also somewhat common to find still if you are on the fence about synthetics and their cost.  5w-40 is a very common weight in a synthetic or blend.   The 40 may be a little thick for a very fresh engine especially if it was set up with more modern standards but once you get some miles on it should be fine.

I keep forgetting to look when I'm at a dealer but someone told me that one of the tractor companies branded oils carries an SF rating which was in the 80's when just about everything on the road was flat tappets.  I don't remember the brand but I was thinking it was one of them like Kubota.  I was told it was because they didn't go to rollers till into the 2000's so you will often find 2 oils on the shelf for them a pre and post 2000.       
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

signart

never too early in the oil thread to insert, I hope...
Art D. Woody

Dr. John T. Welch

After proper break in, Valvoline VR1 Racing Oil 10W30.  Available by the case at Walmart.
John T. Welch
CLC   24277

cadillacmike68

#6
I use Shell Rotella T4 T5 or T6 (reg, syn blend, full syn). I use 15W40, because it is always HOT here in FL. You might want a lower number than 15W depending on where you live.
Regards,
"Cadillac" Mike

"Cadillac Kid" Greg Surfas 15364

I second VR-1.  Use it in both my flat tappet and roller cam 500's.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

scotth3886


mike mason

Had been using synthetic oil for a long time, no damage or wear.  But after engine work, and homework, switched to Valvoline VR1 because of the high zinc content.  AMSOIL also has a high quality zinc oil for needy cars, but not available at Walmart or Napa.  I buy it by the case too. 

dadscad

Quote from: mike mason on July 30, 2020, 05:45:54 PM
Had been using synthetic oil for a long time, no damage or wear.  But after engine work, and homework, switched to Valvoline VR1 because of the high zinc content.  AMSOIL also has a high quality zinc oil for needy cars, but not available at Walmart or Napa.  I buy it by the case too.

I'll second for Amsoil, I've been using Amsoil in everything I have since 2002. Obtaining oil from Amsoil is as simple as pie by ordering on their website. Most orders are shipped and delivered in a couple of days. I have put hundreds of thousands of miles on vehicles using Amsoil products. The Amsoil ZROD line is specially formulated for the antique auto applications.
Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille