oil recommendation for flat tappet cams

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Mar 26, 2003
Central Illinois
Is an SL rated automotive oil what I should be using in an old iron V8 with a flat tappet cam? After reading about the reduced level of anti wear additives in current "S" oils, I am concerned that these may not be what I should be running. Others have advised to use a 15W40 oil as this type has much higher levels of anti wear additives to promote longer cam/tappet life. I would like to stay away from 20W50 racing oil if possible, especially in colder weather.

Now to complicate things even further, many of the aftermarket cam manufacturers advise against synthetic oils when running their flat tappet cams. They even recommend a straight weight 30 or 40 wt non-synthetic for camshaft break-in. After the cam is broken in they say any non-synthetic multi-vis is ok to use.
I have used crane,comp and isky none have said in their instructions not to use synthetic oil after breakin.

[ March 28, 2003, 12:05 AM: Message edited by: Steve S ]
I'm using Mobil Delvac 1300 Super 15/40 in the 351C4V in my 70 Mustang Mach 1. I am planning on switching to a Redline synthetic 10/40 after a little more break-in. It is only summer driven so cold starting is not of concern to me. I was using a passenger car only 10/30 but was concerned that it was thinning out a little too much at temperature. It gets quite warm inside those old V-8's.
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