My reason for asking is Corvette Etc in Charlotte is dropping in a new GM 350/195 crate engine into my 1981 Vette and it has flat tappet cam and since most of today's oils are minus or very little Zinc and Phosphorus additives, what are you using? Brand and weight range would be good to know. This will not be for breakin period, but for after breakin running.   

I went to a fully synthetic 5 wt. 30 Pennziol Platinum on my last oil change. I also started using a product called CAM-SHIELD premium ZDDP oil treatment which is supposed to replace the zink & phosporous missing in todays oils that older cars without catalytic converters need. I don't know if it helps but I figured it couldn't hurt.

Well I still have the catalyic converter on......would that make a different?

Yes, I just read the warning on the bottle of cam-shield. It says thi it will cause irreparable damage to the converter.        

I do not put many miles on my vette in a season so I use valvoline non syn oil. I researched oil test's and found Valvoline to be leading the way.

Amsoil full synthetic SAE 10W-40. in my original engine. Has zinc in it and says it's for flat tappets. I think their 10-40 is the only weight with zinc. Check their web site. Can't tell ya on the cat, I aint got one, either.
http://i159.photobucket.com/albums/t132/JeffsVette/Vette%20Misc/amsoil.jpg

I love this question..in your instance the amsiol or other synthetics that run the ZDDP in them will be fine..if you had an old engine I would avoid synthetics only because they create or find oil leaks..I run Valvoline VR1 20-50..I use that weight because I run the car hard and only in the summer..I do 3 k or so a year..but like some..I still change it 3 times in the summer..makes for good beer convo in the garage..have fun.

Rich

Valvoline 10-30 in the summer with the Lucas Oil Stabilizer for the zinc.

Penn Grade #1 high performance green oil, Website information
I also add 1/2 bottle of Lucas ZDDP additive.
Rodney

 Castrol 10w-30 in winter, 10w-40 in summer with a bottle of ZDDPlus at every oil change.