The book says API SF 30W oil. I can find the OMC version for $5.50/qt. I did not find any other oil that was SF, or the other specs. most oil containers only had that the oil was great and met specifications, but did not say what specification. Is there any alternatives? like the synth oils? And since this is an older engine , is straight 30W good enough?<br />Any suggestions on a good oil and filter would be great.<br /><br />1986 EbbTide 4.3L 2b.