What oil in 600's?
 

What is the absolute best oil to use in Mercruiser 600's? We use Mobil 1 in the other 3 boats (Merc 5.0, Merc 502, merc 496's)

Everyone will agree that mobile one is good. But if it is labeled by the API certified for a passanger car, I would not use it. It does not have enough anti-wear and corrosion resistant additives. If price was no object, I would go with the "Joe Gibbs" labbled oil. Since I cant decide myself, I wound up running Merc's Semmi Synthetic.
Jr.

Your manual states Kendall 20W50. That would be a good choice for a conventional oil. Otherwise, I would run 20W50 Mobil 1 V-Twin.

we want to use a full synthetic

Then Mobil 1 V-Twin 20W50, Red Line 20W50, Amsoil Racing 20W50 would all be good choices. Mentalpause who has the first F-4 Sunsation is running V-Twin in his 600's with good results. Carries a ton of oil pressure after running hard compared to other oils.

Im at Mobil 1's website and I dont see the V-Twin or any 20W50 on there? Thanks for the responses!!

Edit: Nevermind, found it in the motorcycle section

Mobil 1 15/50 is what I use in my 525SC and change it every 25 hours. The old version(less $$) is back at Walmart in the 5 quart jugs.

Correct, it is a motorcycle oil and not subject to the latest emission requirements. We have run it in several race cars with excellent results.

Thanks again, Didnt see it at walmart. Would most auto stores carry it?

Mobil 1 VTwin 20W-50 or the new Mobil 1 Silver Cap 15W-50. Read Hydrocruiser's thread.

O'Reilys and Advanced Auto carry it. I'm sure others do as well or can get it for you.

What ever you go with...a blower means changing the oil every 20 hours...

I would go with 20W-50 Castrol or M-1 15W-50.

V-Twin/Amsoil Racing or Redline 20W-50 is price if not an issue.

20W50 Castrol? I looked at a bottle and it is API SM rated. Doesn't that mean it has reduced levels of ZDDP? I know Kendall 20W50 is still API SJ rated.

I've been running the Castrol 20w50 for the last 5 years in non-blower engines with great results. I buy it in the gallon jugs at Advance auto parts and change it every 25-30 hours.

Do I really need a multi vis oil? what is wrong with a straight weight? I do not care about how the engine warms up at idle when it is 5 deg F out.

Does anyone make a good straight weight? Hydro would know. The best all seem to be multis.

I asked the Merc Dyno guy last week as he was running in a set of 600SCi's and he said "Kendall GT1 20w-50 is all we should ever use."
No synthetics!... he was adamant about that, I asked why and he said "It F u c k s with the rollers on the lifters and rockers."

.......causing flat spots because the rollers are sliding and not rolling? If they are sliding on an oil film, where does the wear come from? harley said the same thing with their engines with roller lifters and synthetic oil............................until they came out with a synthetic.

Ken

Teague used to state this too awhile back but hasn't mentioned much about it lately. I personally know of a pair of 454 MAG's with roller cams that had 420 hours on 15W50 Mobil 1 and never had a problem. What never made sense to me about this statement from Merc (and from Bob Teague) is that if the oil is so slick as to not allow the roller tips on the lifters to roll, how can there be enough metal to metal contact to cause wear patterns? How do Corvettes and Vipers on the street running synthetics not have the same problem? I can't imagine the valve spring pressures on marine engines are that much greater than in those motors. Who knows...

Low Moly oils are less slippery, like VTwin, and help with this theoretical "problem". I read this on this thread someplace.

I think Harley is using a synthetic blend