Re: Recommended oil for a 352 (56 Super)

Posted by Tim Cole On 2022/9/16 8:45:49

15W-40 is a low rpm diesel oil. With the Olds pump the primary drawback is excessive wear on the distributor drive and lost power due to pumping loss. With the stock pump it is not advisable given the pump is designed for 20w oil (ie distortion of the pump body).

Starting after the API SJ rating zinc levels were decreased. So for example, lawnmower oil that is sold as such is an SJ rating. Thus, the lawnmower makers want the zinc.

On the earlier Senior Packards I doubt the zinc matters because they have soft valve springs and rocker follower rollers. For the V-8 an oil closer to as built probably is a better fit if the car is being used for a lot of highway driving. As well, these modern diesels have diesel oxidation catalysts and particulate filters so the zinc content of those oils is subject to that consideration.

You can buy the zinc additives or SJ rated oils from firms such as Lucas and 10w-30 is a fair choice given Packard specified 20w for that engine.