the info i have is not all mineral oils and synthetics are created equal any more as far as ZZDP is concerned and you should be careful. i was using Castrol syntec but found it has LOW amounts of ZZDP.
i have found that Royal Purple synthetics and mineral oils have kept there ZZDP levels. here is a copy of an e mail that royal purple sent me after i asked for more info.
the problem with Rotella is its a deisel motor oil and it isnt really formulated for gas engines.
heres the e mail info.......
Oils that you should stay away from for a flat tappet cam engine would be multiweight SAE 20s (0W20, 5W20) or multiweight SAE 30s (0W30, 5W30, or 10W30) that claim to meet the API SM Service Classification. These grades with an API SM license are restricted to 800 ppm of ZDDP which is a drop of over 25% from the API SL levels.
This is true for any conventional oils and synthetics.
But they is nothing wrong with these oils its a miss application to use these oils in your 69 small block no different than trying to use a metric lug nut nothing wrong with it just not appropriate for the application.
Stay with an API SL rated oil in these lighter grades if that is what you want to run such as the RP 5W20, RP 5W30 or RP 10W30 which have 1100 ppm of ZDDP or use a diesel rated oil of CI-4 or CI-4+ such as the RP 10W40 or RP 15W40 oil to get 1300 ppm of ZDDP.
We also offer a racing / street version called XPR available in a 5W20, 5W30, 10W40 or 20W50 all of which have 2000 ppm of ZDDP.
RP has not reduced any levels of antiwear and weve got you covered whether in our SAE street oils or the ultimate the RP XPR Series.
In addition to the stout robust antiwear additives all RP fully formulated motor oils also contain our advanced proprietary additive technology called Synerlec which gives our products literally 4 times the metal to metal oil film strength of other oils.
I do not recommend using the RP Break-In oil as a concentrate / additive. It is a 10W30 mineral oil.
It is not a boosted concentration its actually two steps backwards from our standard product not where you think you want to go.
The RP Break-in oil is not a synthetic base stock as many end-users and engine builders believe that an engine cannot be broken in on a synthetic oil we took that out. Since piston ring seating is desired during the initial break-in of an engine we also took out the Synerlec additive technology to allow the rings to scuff and seat.
Using our street oil will give you 4 times better metal to metal than any synthetic 5W50 I know of on the market of which there are not very many anymore M! makes a 15W50 whos 5W50 are you using and why do you feel that you need such a heavy oil for a small block engine? Do you have large main bearing clearances in a rebuild?
For a stock 302 / 350 the RP XPR 5W30 or RP XPR 10W40 would be the trick oil to use.
In the SAE oils, the RP 10W40 or RP 15W40.
If you got a big block with larger main bearing clearances (>0.003), stay with the multiweight 40 in either the RP XPR 10W40 or the RP 10W40 or RP 15W40
hope this helps.....