1992 Four Winns Horizon 190 with OMC Cobra 5.0L: Engine Oil and Outdrive Oil recommendations?

[JD911]

Hello all,

I recently acquired a very good condition 1992 Four Winns Horizon 190 with an OMC Cobra 5.0L

This is my first boat and I’m trying to get it ready for the summer. It only has 140 hours on it, but it has been sitting in a garage for 10 years so I’m going through it and doing all the maintenance to make sure it’s good to go.

I have a couple questions that I’m hoping you all could help me with:

1. The manual calls for SAE 30 engine oil. I can’t find this in stores anywhere near me. The old owner did have a brand new case of Mercury 25W-40 4-Stoke Marine Engine Oil, is this okay to use?

2. I want to change the gear oil on the outboard. The manual says “OMC HI-VIS GEAR CASE LUBRICANT”, but I’m reading around that this has been discontinued/replaced/not made. What should I replace the gear oil with? Is “Merc High Performance 90 WT” okay?

3. On top of the engine oil and oil in the outboard, I’m replacing the spark plugs, fuel filter and water pump impeller. Can you guys think of anything else I should do before trying to get this into the water?

 

[Bondo]

Hello all,

I recently acquired a very good condition 1992 Four Winns Horizon 190 with an OMC Cobra 5.0L

This is my first boat and I’m trying to get it ready for the summer. It only has 140 hours on it, but it has been sitting in a garage for 10 years so I’m going through it and doing all the maintenance to make sure it’s good to go.

I have a couple questions that I’m hoping you all could help me with:

1. The manual calls for SAE 30 engine oil. I can’t find this in stores anywhere near me. The old owner did have a brand new case of Mercury 25W-40 4-Stoke Marine Engine Oil, is this okay to use?

2. I want to change the gear oil on the outboard. The manual says “OMC HI-VIS GEAR CASE LUBRICANT”, but I’m reading around that this has been discontinued/replaced/not made. What should I replace the gear oil with? Is “Merc High Performance 90 WT” okay?

3. On top of the engine oil and oil in the outboard, I’m replacing the spark plugs, fuel filter and water pump impeller. Can you guys think of anything else I should do before trying to get this into the water?

Ayuh,..... Welcome Aboard,..... Yer choices are just fine,..... I use 15W-40 diesel motor oil in my motors, 'n 'bout any full-syn 75W-90 in my drives,....

I'd probably pop the distributor cap for a peek, 'n pull the drive to inspect the rubber bits, 'n grease the u-joints, 'n drive splines,....

 

[Lou C]

You can use that Merc 25/40 I have used it for a long time, the OMC gearcase lube is now BRP HPF gearcase lube, it is not easy to find, but you can use the Merc High Performance gear lube, I have used that in my Cobra for close to 20 years. If this is the dog clutch Cobra (the drive is flat across the top) make sure to follow the manual for re-filling.
Other things to check are the raw water impeller, on a '92 OMC that would be in the upper gearcase of the outdrive, behind a plastic cover. Very easy job.
Might also want to pull out the thermostat and test it to make sure it opens at the right temp (160*).
Look at the joint between the exhaust manifolds and exhaust elbows, if you see rust trails, you should plan on replacing the gaskets between them but also check the sealing surfaces.

 

[ScottinAZ]

I also use the 15w40 (either Delo or Rotella) in my boats (and most of my other vehicles as well). Again, I also use a synthetic gear oil in my outdrives.....

Some may argue, but more equipment has been ruined by NO OIL, than has ever been damaged by the WRONG OIL.... change it often, check it for water, and you should be good to go.

I just got done changing the rubber parts on my 1995 Cobra that has been off the water since at least 2017, and while "old" were still "serviceable" with no signs of water intrusion where there shouldnt be.... Check'em often, and change when needed. I usually dont go much past 3-5 years just for peace of mind.... the pump impeller though is a yearly replacement. Cheap insurance against problems. On both iterations of the Cobra, they are dead simple and accessible, so no reason to risk it....