flathead oil

[uncle buck]

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]

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%20-%20ZDDP%20and%20Engine%20Break-in.pdf

 

[40Coupe]

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