flathead oil

[29 special]

just finished rebuilding my 8rt does anyone use detergent oil in a clean flattie or is it best to stay with straight weight thanks

[paul2748]

Use detergent, it keeps the engine clean - 20/50 or 15/40 (Diesel) is my recommendation

[29 special]

thanks paul

[Binx]

Here we go again........

[Fibber Mcgee]

Am I the only one who gets nervous when I see the word oil in a post?

[19Fordy]

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I use Castrol 20W50 along with a bottle of STP that contains ZDDP. Some folks say that using synthetic oil is good also, but it tends to find "leaks" easier. Seems logical to me that if you have a nice new clean engine that you would wanto to keep it clean by using detergent oil. Regular oil changes are the key.

[G.M.]

Read this attachment to understand a little about oils and decide what you want to use. G.M.

[Old Henry]

Originally Posted by G.M.

Read this attachment to understand a little about oils and decide what you want to use. G.M.

CAUTION: That whole discussion is about oils for diesel engines. Gasoline and diesel oils have different additive packages because the contaminates in the crankcase are different. With a gasoline engine you get a lot of moisture and tar and with a diesel the oil becomes acidic and will collect more carbon.

Many oils will work well in either engine type but it's always best to use an oil specially formulated to the type of engine for optimal life.

You will see things like "API SG/CJ" on the oil container, that means:

API = American Petrolium Industry
SG = Spark ignition, grade "G"
CJ = Compression ignition, grade "J"

The second letter is the grade designator, in alphabetical order, and later = better.

All oils analyzed in G.M.'s article are C grades for compression ignition engines (diesel engines). Not as good as S grades for our spark ignition engines.

[Old Henry]

Here is a very exhaustive thread on the subject from two months ago: http://www.fordbarn.com/forum/showthread.php?t=60100

[40Coupe]

Originally Posted by Old Henry

CAUTION: That whole discussion is about oils for diesel engines.
All oils analyzed in G.M.'s article are C grades for compression ignition engines (diesel engines). Not as good as S grades for our spark ignition engines.

Indeed another oil thread . Here are my constructive thoughts having read many threads on other boards.

Interesting article...I am using oil #17 (Chevron Delo 15-40 400 LE) in my flathead and plan to use it in my Chevy muscle cars this summer to forego adding Zinc for flat tappet cams. Recent articles point to potential for spalling of iron from high levels of additive. A friend is a Chevron employee and recommended this oil as he uses it for his "fleet".
I tried 10-30 as suggested here but was uncomfortable with what I presume was higher levels of valvetrain noise.
Zinc levels are adequate at 1268 for my flat tappet cars and overkill for flatties I suspect..but what I found interesting was this oil's Ho Hum rating as calcium/detergent levels are low at 1593 and TBN low at 7.82. However the author indicates the TBN levels are high for a passenger car!
I then compared to Valvoline conventional API SM/SL 10-30 which has similar levels of Calcium levels at 1620 for autos.
I'm not sure how the oxidation inhibitors the author mentions affect this oil for auto use.

Summary: Whats ho hum for diesels may be adequate for autos....

Lane

[Ol' Ron]

The stock flathead does not have an efeective filter. Using a detergent oil keeps the grit,dirt and other unwanted stuff in suspension so the filter can remove it. A good 10-30 non detergent oill would be best, in my opinion. I also believe that a newly rebuilt engine should be run hard and not spend much time running without a load. After a few 100 miles you can drain this and use what ever oil you see fit for your application. I recommend 10-30 as this is what the Ford factory specs. I feel 20-50 is best used in old warnout engines to keep the oil pressure up.

[uncle buck]

Keep in mind that the feds have required the zinc additives to be removed for emission requirements on the oils of today. I have been told that the changes in the diesel oils have also reduced it too. Make sure to consider adding a zinc additive to whatever you decide for continued cam and lifter life. Lucas, Hiltons and all of the major cam manufacturers offer it. I also have been told that the racing oils still have zinc in them , as they are intended for off road use.

[29 special]

thanks for replies my plan is to use10w30 non detergent drain alitle out each qrt add zinc so it pours over cam lifters when entering motor then check out a detergent oil after break in .I always add zinc long after break in in new motors my first flathead rebuild though tom

[TomO]

Most single viscosity oils on the market are detergent oils. You have to look hard to find a non-detergent oil.

The Multi-Viscosity oils give a more constant lubrication than the single viscosity oils.

[Old Henry]

Originally Posted by TomO

The Multi-Viscosity oils give a more constant lubrication than the single viscosity oils.

Before getting too committed to multiviscosity oils you should read this information about the down side of them: http://www.upmpg.com/tech_articles/motoroil_viscosity/

[flatjack9]

Of course you realize they are promoting synthetic oils. They say viscosity index improvers can break down under high temperature and high shear conditions. How long must they be subjected to these extremes before they break down? They say that when broken down sludging will result. I've run my engine on multi viscosity oils for nearly 20 years now and there is not even a trace of sludge in that engine. I don't think our flatheads are taxing the oils of today.

[Ol' Ron]

I think someone makes a break in oil, but I can't remember who.

[uncle buck]

Originally Posted by Ol' Ron

I think someone makes a break in oil, but I can't remember who.

Royal Purple does. It is NOT a synthetic like the rest of their oils.

[Old Henry]

Originally Posted by 29 special

just finished rebuilding my 8rt does anyone use detergent oil in a clean flattie or is it best to stay with straight weight thanks

Here is a most excellent and exhaustive discussion about breaking in an engine. Page 10 discusses what oil and additives to use - non-detergent, non-synthetic, straight weight for first 45 minutes and why. Pages 11-12 give the spedific procedure for break in to be followed closely and why. I followed this procedure in breaking in my engine and it runs great after 20,000 miles. It may be helpful. Check it out.
http://www.zddplus.com/TechBrief12%2...20Break-in.pdf

[G.M.]

My engine broke in just fine with Castrol 20/50. In over 30 years since start up and driven hard for 110,000 miles there is no sludge, runs quiet and burns no oil driven in warm to hot weather. This was a diesel rated oil for about 25 years until they changed all oil designations about 6 or more years ago. G.M.