Engine oil for OMC Cobra engines

[ACH1982]

Hello,
still confused about the selection of marine engine oils and all the "recommendation" in the internet, I am trying to find the best solution for my boat.
The manual of the 1995 OMC Cobra 4.3GL calls for streight weight SAE30 and not for multiviscosity oils.
Nowadays I can just find marine multiviscosity oils e.g. Quicksilver, Sierra, Ravenol, Rowe and Kroon Oil in the viscosity 25W-40 and 20W-50.
I know, today oils are much better than 1995.

The 20W50 and 25W40 are thick oils, but do they stay in grade and are they comparable with the SAE30?

Btw. I live in europe, so some oils are not available here.


Are there some recommendations for a usable oil for ths engine?

 

[CT8]

Yes and the 15W4-40 HDEOs work well in marine use.

 

[andyd]

If you are worried about 20w50 shearing, change it more frequently. I would talk to some local marine engine techs to get their input. No experience with old boats, just old BMWs

 

[Donald]

Originally Posted by CT8
Yes and the 15W4-40 HDEOs work well in marine use.


+1

Your biggest issue will not be the engine, but rather the outdrive. Mercruiser are easy to find parts for, OMC, not so much.

 

[Schmoe]

run a HDEO 15W-40 and fo'get about it.

 

[Snagglefoot]

If you are worried about it, have a UOA done on it next oil change. ( and then forget about it)

 

[dwendt44]

It's a small block Chevy. Other than running at high RPMs often,
not much different than the auto/truck engine.
15W-40 available everywhere.

My 2¢

 

[ACH1982]

Originally Posted by Donald
Originally Posted by CT8
Yes and the 15W4-40 HDEOs work well in marine use.


+1

Your biggest issue will not be the engine, but rather the outdrive. Mercruiser are easy to find parts for, OMC, not so much.


It's an SX, so all Volvo Parts will fit.

 

[ACH1982]

You guys think 15W-40 is good enough? Isn't it thinner than the merc stuff?

 

[DoubleWasp]

At operating temperature, there is barely a difference. Lots of my customers run 15/40 HDEO and never have an issue over the engine's life.

 

[cb450sc]

I have been using Rotella 15W40 for the past eight years on my 2455 Bayliner. It has a five liter GM engine and OMC outdrive. I was surprised how clean the oil looked when I changed it this fall. Sure sign I didn't use it enough!

 

[Linctex]

Same here.... Rotella 15W-40 or Chevron Delo 15W-40 for many, many years

Use whatever European 15W-40 (or similar) HDEO you can find

 

[Schmoe]

I'm running Delvac 15W-40 in my 3.0LX Mercruiser.....you think that oil gets a workout????

 

[Silverado12]

FWIW I've been using 15W-40 in my 1999 Chaparral 4.3 w/o any issues.