I have an older boat with a Merc 165hp in it and this year was researching oil to use and been going crazy!! Years past I have used straight 30 or 40 weights and last couple years used Mobil 10w40 full synthetic. This spring I just put in some Rotella HDEO 15w40 after hearing good things about it. Then I started reading how the new API rated oils have reduced zinc zddp levels which can harm older motors. So I bought some ZDDPlus additive to bring up levels. Now my question is do the marine oils like 25w40 still have higher zinc levels in them? I have looked all over internet and can't find answer to that. I sent email to mercury marine and got this response:
Thank you for your interest in the MerCruiser product. Regrettably we do not have a chart that would indicate what the ingredients or the amount of each ingredient is in our lubricants. MerCruiser does not have guidelines that would give us indications of safe or unsafe levels of additives or contaminants. We do not base our decisions of engine health on oil analysis.
Thank you for your interest in the MerCruiser product. Regrettably we do not have a chart that would indicate what the ingredients or the amount of each ingredient is in our lubricants. MerCruiser does not have guidelines that would give us indications of safe or unsafe levels of additives or contaminants. We do not base our decisions of engine health on oil analysis.
