which oil for the engine

My engine is a 283 rebuilt sbc. Built to stock specs with 305 heads. I have less than 1200 miles on it and have been using Castrol oil for the break in time. Should I Switch to synthetic or stay as is? Also, which viscosity is recommended here in NC?
Thanks,
Paul

 

I have run Mobil 1 , 10 w 40 in my truck for years with no problem. That said, I use 10 w 30 or 40 Pennzoil in the Jeeps..

 

10w30 is rated up to 85 F while 10w40 is good for higher temps up to 105 F IIRC. So take your pick. Of course in the winter you will want a 0w or 5w for easier starting. I think regular oil is probably good for 5000 mile changes under highway driving and 3000 if you have any harsh conditions like dusty trails, lots of stop and go etc.

I ran a blended part synthetic (7500 miles between changes) for a while before going to full synthetic (generally 10-12,000 between changes) in my newer cars. My BMW however goes 15,000-20,000 between oil changes BUT only with the specific German made Castroil 5W30 that BMW certifies (and NOT the same product bottle made in USA- lab results show they ARE different). In actuality I change it at 10,000 miles and then go to the dealer to get the service minder reset at 20k. It is usually still somewhat clean at 10k-not black and grimy looking. I run Rotella in the truck and Mobile 1 in the Benz and Valvoline in the motorcycles.

IIRC I think the Jeep has regular Penzoil 10w40 in it at the moment and when I change I may step up to a syn-blend

It's pretty much personal choice.

 

I run 15W40 Shell Rotella-T in all the Jeeps. Chevron Delo 400 is also a popular choice.

 

10W40 or 10W30 in a brand of your choice. Synthetic? If you really want, the main benefit is the time between oil changes but personally I change oil often enough its not really worth it to me.
I may switch back to Rotella now that Tim mentions it, I’ve always had good luck with it and my engines seem to like it.

 

I'll toss in my recommendation of the Delo 400, I've run it in lots of stuff and never had an issue with it.

 

isn't Shell Rotella for dieslel engines? I have a 283 sbc.

 

Yes, but it's also suitable for gasoline engines.

Diesel oils became popular for flat-tappet gas engines due to the ZDDP issue. Diesels have piston pin loads that are similar to flat tappet loads, and thus used to have high levels of ZDDP. Supposedly the new API CJ-4 diesel oils have less ZDDP, but Shell claims the CJ-4 Rotella has superior wear and load resistance to the older oils.

 

20w50 here. But the ambient temperature is bunches higher. Been averaging 110 for the last 3 weeks or so.