I have dropped a chev 400 sm-block into an old chev '61 pickup, now it is time to change the oil. I'm thinking I should use a non syn straight 30 oil, woiuld love to use a synthetic or syn-blend.<br /><br />Comments anyone? <br /><br />Should I use a multi weight, and can I use synthetic?<br /><br />Oh ya, the year of the motor, I think is about a '77 or'78.<br />Thanks