Weight of oil?

[boxfox]

What weight of oil should be used in a 1977 440 that is running a temperature of 215-220?
I am currently using a conventional 20W50.

[Chryco Psycho]

this is a huge issue right now
 there is no oil available that is correct for that engine off the shelf , anyhting with a SM rating will eat the cam sooner or later so you either have to add additives to the oil with more ZDDP or buy Z Alt oil

[hooD]

this is a huge issue right now
 there is no oil available that is correct for that engine off the shelf , anyhting with a SM rating will eat the cam sooner or later so you either have to add additives to the oil with more ZDDP or buy Z Alt oil

would that apply to 72-73 340's as well?

[Supercuda]

Yes, it would. Some new oils have recently been introduced that will meet the requirements of our flat-tappet cam-equipped engines. Do some research. Valvoline racing oils have the required amount of ZDDP, as well as oils from Comp Cams, and some others. Z-Alt was one of the first to address this issue specifically, and is a good benchmark to compare other oils to.

[Bullitt-]

I see Lucas has a High Zinc oil that's not unreasonable...Wonder if local auto stores can get as they carry the brand.
http://www.buylucasoil.com/viewitem.asp?itemid=L10621-5QTS.

[Chryco Psycho]

20-50w oils have lower detergent levels so the oil needs to be changed more frequently

[Jimmy]

What about the Royal Purple oils?

[boxfox]

I have been using the Valvoline VR1 conventional race oil 20w50, so I should be fine then?
Is 20w50 too thick or is it just right?

[Strawdawg]

What about the Royal Purple oils?

The RP racing oils are fine.

[1970 RT Challenger 1970]

Would Mobil 1 Synthetic 10W-30 work?

[Strawdawg]

Would Mobil 1 Synthetic 10W-30 work?

no, it is low on zddp, but, Mobil1 15-50 has a good dose.

[boxfox]

I heard its bad to run any kind of Synthetic because the molecules are smaller and will slip past a lot of the big components in the older engines without helping them move around or giving the protection needed.
Anyone else hear this?

[MEK-Dangerfield]

I heard its bad to run any kind of Synthetic because the molecules are smaller and will slip past a lot of the big components in the older engines without helping them move around or giving the protection needed.
Anyone else hear this?

I have heard you shouldn't run synthetic the first couple of thousand miles. I run synthetic in mine with no trouble. Just look at the label for CI-4 rating or if it says added zinc phosphorous or ZDDP. Also, don't go with a light weight oil like they use in modern cars. 5W-30 won't cut it.   

[BIGSHCLUNK]

  absolute minimum 15-40, but I'm currently running 20-50 zr-1. 

[vinb]

I have been using Mobil Delvac 1300, 15-40  CI-4 PLUS rating..