Engine oil convo with my neighbor

zaverin1

i don't run merc oil in my engines but run hd 30 oil either by castrol or penzoil
some people swear that engines run better when using the quicksilver mix.
if you look at the specs straight 30 is what it calls for.

randy56

I run 50 wt penzoil.

06Rinker270

Why not run Merc oil?

Black_Diamond

100 people, 100 answers on oil. I know a lot of people who run 30wt diesel oil (high zddp additive - bad for engines with cats tho!). I run 15w-50 Mobil-1 (high zddp too) in my 350 MAG MPI. In the end, oil/filter changes make all the difference. 

212rowboat

Zddp is the old way of doing it. Sodium and borate are the new.  I'm running Schaefer 9k supreme in 5w40 in mine right now, same one I run in my diesel... with a shot of archoil 9200... I've never seen oil analysis as clean as that combo.  Given, the diesel runs a 2um absolute bypass filter, but I've been told by the labs to run anot her 5k miles on 15k mile oil... I just can't bring myself to do that. 15k is my limit.  

As you know I've repowered with a hotter engine, and one that should be able to tolerate 6k rev mechanically (but spark starts spraying around 5500rpm as it turns out)...  I'm running the Schaefers but less the archoil until I pass 20 hours. It's on its second change right now at about five hours. I wanted that builders lube out. The rings haven't seated yet as is apparent by the even banks blowby, but I have confidence they will.  I can't wait to get a analysis from above 20 hours to about 50.  I hope that comes out is as good to my floater as it is the powerstroke.     

The more I read at bobistheoilguy,  the more convinced I am that the marine heavy (while cold) oil is to keep water from infusing, then hoping to steam it out asap.  The 30w's are absolutely capable of lubrication and transferring heat as any 40 or 50. 

pault1216

My 2cents-My authorized Mercruiser mechanic only uses Castrol 30W however I have only used the recommended Mercury brand 25W40 and have never had a known oil issue. -Paul

Black_Diamond

It is honestly rare you can trace engine wear/failure to the oil itself. Unless it is dirty/old/low. Oils today from major manufacturers is all high quality, they all play with additives. Clean oil and the correct viscosity are key. 

212rowboat

good post B_D.... accurate and sensible...