Break-In and Engine Oil.

[Brass]

All, how long after breaking in the cam should the oil be changed?  I've heard anywhere from immediately to 500 - 1000 miles...  

Also, after searching this forum and reviewing websites, I still don't know what engine oil to use after break in.  (Frustrating.)  I finally decided on regular (non-racing) Royal Purple 20/50 with zddplus additive.  But then I was told a number of times that I shouldn't use full synthetic because it finds leaks.  (My engine has a new rear main seal - but the crank is a little rough around there so I am concerned about that.)  Crower also doesn't recommend synthetic oil.  Moreover, I keep hearing that 20/50 is too thick.  (wtf?)  I'm skeptical because the way people make it out to sound, there is absolutely *no* appropriate time to use 20/50.   There are videos on Royal purple's website refuting certain claims but they were probably commissioned by RP.  Again, I'm skeptical.

Alternatively, I am thinking of using a blend like Brad Penn and being done with it...  In that case I'm guessing no additive would be needed(?)  (Over 1700 ppm is probably too much.)

Anyway, I would be interested in hearing exactly what some of you are using.  Thanks!

[Rayzor]

I would give the engine a few hundred miles on the current oil. That way your seals can swell and rings will be well seated before slicking it up with a synthetic oil. Also it takes awhile for the assembly lube to disolve away and mix in with the oil. I personaly like Mobile 1 in 10-30 and run lucas zinc additive. I would think 20-50 would be to thick for good fast flow and splash oiling. It also will make the oil pump work harder to spin the thick stuff costing you some power over a thinner weight.

[flyinlow]

When I broke my mild build 446 , hydrualic flat tappit cam in I heated the non detergent sae 30 with Comp Cams break in addative and poured it in the engine. Pre oiled with a drill while cranking engine over for a few seconds.

Started, leak checked , quick timming. Then did a 30 minute above idle engine run. Follow cam manufactures procedure.

Changed oil. dark and silvery.

Installed 10w-40 non synthetic + Comp Cams breakin lube. Drive 500-1000 miles and change oil.

Installed 10w -40 Mobil 1 + break in lube. Normal drain interval.

Drive 100,000 miles, re-evaluate oil choice.  9000 miles so far.    

The lower number oils flow better on cold starts when alot of the engine wear occurs, but our engines have looser bearing clearences and enlarged oil passages. I would think anywhere between a 10w-30 and 20w-50 would work in my engine with the limited number of below freezing starts it will see.

I would not give up the addvantages of synthetic oils even if it did make my seaks leak a little.