OMC Cobra 4.3 Oil ?

[tdawgcj7]

Last year i picked up a 1987 starcraft with a OMC Cobra 4.3 stern drive.
Not sure what kind of maintenance was done on it, but i am about to do the works.

Changed the plugs yesterday, ouch... not good. Now a nice set of champions with the right gap.

Next i am replacing the filter with a Sierra 18-7879. The book recommends Cobra SAE 30 engineer oil. I actually found this by the gallon at a local boat store, but the salesman did not recommend it. He is recommending SYNTHETIC BLEND MERCRUISER (25W-40). I am suprised he didn't just sell me the cobra oil since he was out of the mercruiser.

Is it ok to use this oil? My book puts a high emphasis on using a straight weight oil.... is the book just old?

Thank you
Justin

 

[danond]

Re: OMC Cobra 4.3 Oil ?

Straight 30 weight synthetic works great. Follow the manual.

 

[tdawgcj7]

Re: OMC Cobra 4.3 Oil ?

The only straight 30 that i am finding in a synthetic is Amsoil diesel.
http://www.synthetic-motor-oil-chan...l_products/amsoil_sae-30-product-code-acd.php

I hope i didn't waste my money order the mercruiser oil from west marine.....

 

[Lou C]

Re: OMC Cobra 4.3 Oil ?

In an engine that old (I have one too, an '88) you don't need a syn or syn blend, I have used Chevron Delo 400 in straight 30 for the past 6 seasons, and it works great. It is a heavy duty diesel oil that can be used in gas engines too and is perferct for I/Os and inboards where a straight 30 (or 40) is recommended. You can use any heavy duty straight 30, Shell Rotella, Pennzoil Marine 30, etc. The Merc oil would be fine too, but it's a buck a quart more last time I checked.

Now for the lower unit, if you change the oil in it, OMC specified their Hi-Vis oil which can be hard to find, but Evinrude dealers do sell it. My mechanic recommended the Merc high performance gear lube which is what I use and it works fine. BUT, you must change the oil the OMC way not the Merc way.

www.crowleymarine.com
Look in product support, OMC Cobra drives, the procedure right from the factory shop manual is there, also they have the R+R procedure as well.

In any I/O boat where you don't know the maintenance, it's recommended to remove the drive to check the bellows and lube the ujoints, splines and gimble bearing.

And finally, for spark plugs the AC marine MR43T works good in that engine. It still has a points ignition so they may have to be adjusted. Just did mine on this past Saturday.