Re: sae 30 vs 10w30
Well,
I'm not talking about this thread (yet)...
If you take a look at "oil' threads here and on other forums.....some have gotten VERY heated and emotional.
It's just oil. Change it regularly, Use the type that the manufacturer suggests (today) , Go boating. It's about that simple.
Nowadays the manufacturers suggest multi grade. They do that because the oils have improved over the years.
The multigrades actually do reduce fuel usage because they are less viscous prior to getting to normal operating temps (unlike single grades)
Less viscous also means faster oil flow and less friction during cold wx start & warm-up etc.
It's probably less important in a boat since they're not usually operated in temp extremes like cars and trucks are.
This is not a new concept. Some aircraft engines back in the "old" days had an oil dilution system that dumped gasoline into the oil (pilot controlled) just prior to shutdown in freezing weather. The next morning, during eng start the oil would flow immediately to the bearings etc since it was pretty thin.
the gasoline would evaporate when the engine warmed up (DON'T ANYONE EVER TRY THIS IN ANY MARINE OR AUTOMOTIVE ENGINE!!!!!.......you just might blow yourself up! )
(the oil pressure gage by the way didn't tell you much since the sender was located in a main oil passage......like just about all automotive and marine engines.......it only told you that the pump was producing pressure......It didn't tell you that there was NO oil flow to the main and rod bearings etc)
That was in ancient times. Nowadays the aviation industry has multi-grade oils. Oil dilution is not used anymore. A lot of people still use single grade oils though. Preheating is popular. I guess we don't do this in boats either.
Anyway everyones dad, uncle, mechanic, etc... has an opinion on oil.
Here's what Mercury Marine says from
http://northamerica.mercurymarine.com/serviceandwarranty/mercruiserfaqs/fueloil.php
To help obtain optimum engine performance and to provide maximum protection, we strongly recommend the use of the following oils listed in the order of recommendation:
1. MerCruiser / Quicksilver Synthetic Blend, NMMA FC-W rated, 4 cycle oil.
2. MerCruiser / Quicksilver 25W40 NMMA FC-W rated oil.
3. A NMMA FC-W rated oil.
4. MerCruiser / Quicksilver 4-cycle 25W40, non FC-W rated oil.
5. A good grade straight weight detergent automotive oil per the operating chart below. //SNIP//
It's hard to disagree with the Quicksilver people!
Regards,
Rick
