the tests are recent(3 t0 4 years) the tests on new and old rotela t diesel lube is a indicater as well as results for joe gibs race oil,how long has he bine in nascar would be a guage.
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I have found reading all the test numbers interesting but I wonder what these numbers might have been on the old oils we ran in the 60-70's as a comparison. I had built and ran numerous Yblocks and FE's during that period and always used 30W Vavoline. People used all different brands during those years and I don't remember any cam and lifter failures, I never had any.

the lab tests i have quoted ALS Tribology, sparks nevada usa indicate load carrying capacity which efect camshafts and the other rotating components,as well as temp. when thermal breakdown starts. for example shell rotela t 15/40 hsa72022psi load capacity,thermal bd 250d 2886pm detergent
older rotellat 71214psithermal bdown 250d det 2715 pm.. so this is contrarey to bearing wear would occur do to detergent.
now look at oils that ar for s(spark ignited engines) des.  mother craft 5/50 103517psi
   5/30 sheveron supreme conventional 100011psi zink 1018ppm  phos ppm 728 molley161ppm
5/20 castrol gtx covemt 96514psi zink610 ppmphos754ppm  molley94ppm.  the tester goes on to scythe aditive packages ar different load noes are the key,as aditives ar used up change  intervals com into play.the paper goes on to say diesel engine oils ar ok but are no wher nears coded motor oils for gas enginesespecialley whe flat tappet cames ar in play. those who has good results with oils like rotela t wher probebley mild  n performannce and worked ok,but with less insurance frome dry starts, stickey valves ,poor oil supply to rockers etc. when i was working the co sold shell products, we wher cautioned not to use rotelat as it could harm f tapet cams. the need for more detergent was due to exhaust recerculatiom to meet present env. laws. created moer slidge etc..i found this paper very informative , but lots of reading. finally lecters on ignoring gosip and get facts from magor oil cos.

Well,I have used 20-50 Castrol GTX in all my hot rod engines flat or roller tappet for a very long time now both as break in oil and for regular use.Before multi grade oils were commonly accepted by rednecks like me I used Kendall 30 wt.These days I use 2  ounces of redline zinc additive at each oil change.I change oil and filter in my Y block at 2000 mile intervals .I realize that is more than needed,it just makes me feel better.Initial fireup on a fresh engine I pre oil the engine in the usual manner ,fire it up and run it at  varying rpm between1800-2200 for about 20-30 minutes .I have never had a problem doing it this way yet.I suspect that proper assembely lube and pre oiling are the really critical items.I use a lot of cam assembly lube on the cam lobes and lifter faces.

So synthetic oil is good to use in a flat tappet cam engine once run in?
Or would it be better to just stay with a mineral oil?
I used a run in oil 10/40 for about 400 miles and now running a full synthetic pao/ester 15/50 oil.
Penrite the oil manufacturer I'm using list 20/60 semi synthetic for the y block.
I guess as teds "eaton balancing" blog suggests regular oil changes At 3000miles is as important.

For flat tappet camshaft break-in, it’s important to use a oil that has high shear properties.  If the oil is ‘too slick’, then the lifter will simply slip on the camshaft lobe and not rotate.  It’s because of the reduced shear properties in synthetic oil that it is not recommended for a flat tappet camshaft break in.  Another general rule for flat tappet camshaft break in is to not use an oil with less than 30 in its viscosity rating (ie: 30W, 5W-30, 10W-30, etc) simply due to oils with less than 30 also having reduced shear.  While some of the diesel oils available have a zinc/phosphorus content suitable for flat tappet camshafts, the detergent level is considerably higher thus promoting increased wear on the engine bearings in a gasoline application.

Lorena, Texas (South of Waco)

It wasn't very long ago that people and some cam manufactures were blaming cam and lifter failure on a lack of Zinc in newer oils. That was one of the reasons people started using the diesel oils, as did I. Right or wrong I can't say but I can say I haven't had any issues using it.

ther is a big list,if you choose to learn go to the site,dello 400 is ok but sure not the best  dello 400 has a load max of69367psi,rotellat is67804.
mobil 1 is82263, psi    890pm zinkmoley819ppm phos819ppm
20/50 castro lgtx 96514psi zink610ppm phos754ppm moley94 ppm thes ar some of the test results.
oil categories for gas  arover90000psi, out standing
75000-90000 good protection
60000-70000 modist
60000unexceptable forgasengines ,esp flat tapet. just afew frome the toatle test results

Show me an auto oil that has a better additive package then these, especially the Delo 400
The Petroleum Quality Institute of America

send me your email and i will email the whole adress,cant understand why the site changes the adress,as if 1 uses the whole adress ther ar several sites canadian and us.cliff ct1940@shaw.ca