After my engine breakin, I've been running Mobil 1 10W30. My Melling oil pump is hi-volume not hi-pressure. I have 35pounds at idle and 50 at 3500RPM.

 

If you bought your engine from somewhere then ask the builder what oil to use.

For OEM engines the viscosity is determined by temperature.

Here's what the book says:

http://ecs.csus.edu/~woodst/oil.jpg

 

If you bought your engine from somewhere then ask the builder what oil to use.

For OEM engines the viscosity is determined by temperature.

Here's what the book says:

 

Thats what I use in my early 350HP SB.
Synthetic is out of the question. The engine was fresh and didnt leak a drop. when I bought the car 5 yrs ago and I immediately Put Mobile 1 20/50 full sythetic and headed out for hot august nights car show in reno. I was leaking a quart every 200mi. and leaving a puddle from the rear main seal drip in everyones driveway that I stopped in..I Limped back home put seal conditioner and fresh 20/50 fossil in it 3 times before it stopped leaking.
Tom

 

A 327 crank in a 283 block equals 307cid. The 305 has a 3.48" stroke crank in a block that had smaller bores than the original Small Block the 265.

BigBlockk

Later.....

 

I "like" high oil pressures at medium and low speeds on the street. Primarily because of solid roller cams with pressurized oiling to lifter axles. If I had the EDM holes in the flat tappet lifters, I'd want the same thing.

But frankly I've always preferred higher oil pressures.

There is for sure some HP to be gained with lower pressures. I've witnessed dyno tests with externally adjustable oil pumps where it was a 20+ hp swing between high and lower pressures at high RPM. But remember, this is race stuff....these guys run 40 psi Max at 9000+ rpm on big block Chevy's. But they also don't spend much time warming oil etc. They use oil that is literally "0" weight..it's like water and holds 3-5 psi at idle tops.

When oil is hot there is a huge difference in viscosity. Since I do lots of street driving on highway and traffic...I use 20/50 in my 540. It has pretty much stock clearances and gauge is definitely on the far right most of the time. I've played with other weights...even at the track...I've yet to duplicate anything like they say in magazines with lighter weights or synthetics at track or dyno.

No doubt synthetics are better at extremes...but by the time my oil is 400*...I hope I'm smart enough to have shut it down. There are lots of other issues before thast happens!

There is merit to the diesel oil as well as the additives with additional Zinc in them. Most of the 'good" stuff is out of your typical street oil...the stuff that says for racing and not for street use still has good stuff in it. Need to change it regularly...it doesn't have some of the newer additives in it either for increased changes.

JIM

 

I'm running Royal Purlple synthetic 10/30.and I'm reving to about 6800..

 

As someone else here mentioned use the weight oil which gives you good Oil pressure for what demands you make on it. There are tons of factors that effect the weight of the oil. Just two are Temp,bearing clearance.

As 427 HOTROD and myself and a few others are in South Texas it gets HOT down here so we stick with the 20-50 weight range. I have used Castroil 20-50 for years and it has never let me down. Even in my old Saburban with 320,000mi it still runs great. The Key is change your Oil. Years ago I did some testing with Valvoline,Quaker State,Penzoil, Havolin, And Castroil and found all the others under heavy use broke down real fast and lost Oil Pressure where as the Castroil did not. I also found if you substitute just 1 Quart of pure synthetic in a race motor mind you it can add 7HP. Just a little info out there.

 

The more I drive it the more I like the new 5W-50 full syn Castrol in my 427ci

My oil press at @200 degrees is 30 ish at idle and it climbs to 75 or so at 5000+ rpm.

It's thin enough to lube everything at that up and is only 40-45 cold and within two minutes is coming down.