what engine oil do you use?

[69coupe]

What engine oil do you Guys use for street use ??
Also do you use a different oil to run a new engine in and switch later with the filter after intial fire up and the cam is run in
I use to use full 50 weight Penzzoil for racing but sometimes needed to heat the sump before firing on cold days- no good for a streeter !!

[anychevy]

I normally use Penrite HPR 50 -(40w70) but recently tried Pennzoil GT-20w50 and found a slight loss in oil pressure @ idle (5 psi) when hot, compared to the Penrite.
My BBC has a few miles on it as well, so I'll be going back to the HPR 50 next change.

For cooler climates I would recommend the pennzoil if your worried about high oil pressure when cold ?
Depends alot on engine age, size, tolerances etc. but they're both good oils for a street engine

But then we can get into the whole "synthetic verses mineral" arguement, so I would be interested in hearing more opinions on that as well.

I hear "Royal Purple" is the oil of choice now, if you can afford it ?

As for "Break in" oil ? I would think any 20w50 would do, but I'm no expert.

[john pony]

I use Castrol Edge SAE 5w-30 and the dealer Mustang Australia use Penrite 5w -30 and Ford USA recomend SAE 5w-20. But All the forums in the states say "Royal Purple" SAE 5w-30 is the best to use as performance is the same but the 30 protects the engine better than the 20.If i see any Royal Purple depending on how much it cost i would get some.