Difference between Engine Oil Types, Marine vs conventional

[jmiller2496]

So the owners manual says use Penzoil Marine 15x40 and that its superior to conventional 15w40 by Mobil or Rotella. But is it? And why? Sure maybe there are some additives that are special for marine but are they really worth it or is it just a bunch of marketing?  

[footndale]

Because Penzoil had an agreement with Indmar.

Use any 15w40 diesel oil. 

[oldjeep]

51 minutes ago, jmiller2496 said:

So the owners manual says use Penzoil Marine 15x40 and that its superior to conventional 15w40 by Mobil or Rotella. But is it? And why? Sure maybe there are some additives that are special for marine but are they really worth it or is it just a bunch of marketing?  

Kind of a moot point now that the Pennzoil Marine 15w40 is nearly impossible to get ahold of.

[electricjohn]

The marine grade oil has a higher total base number (TBN) which counters acidic build up in your oil.  Comes in handy for long duration oil change intervals.