Thread: Chevy 350 in my new 48 buick

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BTW, the casting numbers you gave (3970010) was used for SBC blocks with a 4.000" bore from 1969-1980, could be a 2 or 4 bolt main with the cubic inch of 302, 327, or 350. Look at the machined pad on the right side front of the engine just under the alternator. Look for a 2-3 letter code with a numeric serial number and we can get a better idea of what you have. More than likely the engine does not have a solid flat-tappet cam unless someone put it in there. Back when I was a younger man, it was believed that additives were required. It was also typical for people to run a heavier oil than required to keep up oil pressure (something that I was guilty of), but quality oils of today need no additives.
Most modern engines nowadays use 5W30, but a good quality 10W40 will work fine. I found a long time ago that it does not require a lot of oil pressure, but rather a good flow to all moving parts. I might think a bit differently if the engine was running extremely low oil pressure.

Originally Posted by Hurst01

...... when I was a younger man, it was believed that additives were required. It was also typical for people to run a heavier oil than required to keep up oil pressure (something that I was guilty of), but quality oils of today need no additives.
Most modern engines nowadays use 5W30, but a good quality 10W40 will work fine. I found a long time ago that it does not require a lot of oil pressure, but rather a good flow to all moving parts. I might think a bit differently if the engine was running extremely low oil pressure.

Hurst01, the key to your statement is "...most modern engines", and relative to older engines, an additive or ensuring that the oil selected contains the necessary levels of ZDDP is mandatory if you want the engine to last. At least ten years ago the EPA mandated a severe reduction in the levels of phosphorus in motor oil to protect the more modern (i.e. cheaper) catalytic converters from damage, and to ensure that the catalytic converters would last through the design life of the emissions system. As a result auto enthusiasts started seeing failures in high performance engines in the high friction points like cams and thrust bearings. On "newer" engines OEM's had incorporated roller lifters and roller tip rockers, not only to reduce friction but to support more aggressive ramp angles on the cam profile, so your statement "...quality oils of today need no additives" is correct, but only for engines that are designed to survive with these newer lubricants. If anyone today goes "old school" and runs a flat tappet cam they'll be wise to follow a rigid startup and break-in process, and even then if supplemental ZDDP is not added it is not unusual for a cam to flatten a lobe within a couple of thousand miles of normal service and if that happens that engine will have been circulating highly abrasive metal particles throughout, and will have to be totally torn down for a do-over, ground up. Not only have the engines changed since we were younger, but the motor oils have changed dramatically, too, and NOT for the better relative to the older engines.