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Suggestions on "temporary" oil for 220GPU?


Well-known member
I am working on an older boat that sat out in the weather for years. It had a ton of water in the motor when I did the first oil change. Now that it's running, I think that its picked up more water that was in the oil cooler or other areas of the motor that does not drain out. I noticed a little bit of water in the valve covers after I first got it started, but didn't think much of it. I cleaned it out and moved on.

I only ran it for a few minutes the first time and it was running rough and backfiring through carb. (I now suspect water is partly to blame.) I ran it a little more last night and I could hear the water boiling in the valve covers. So, it looks like I have more water in there than I thought. Water is slowly coming out of blow by. Steam/drip.

So what to do at this point? Should I keep running it so that it boils all the water out? Or should I not run it at all and keep changing oil? I really want to clean the filter and change the oil to get rid of water and certain gunk that's in there now, but I am guessing it will just quickly get water in it again. I have seen all the posts about suggested oil and I plan to keep using Aeroshell. That said, I don't want to dump $80 in oil in there just to have to change it again after 30 minutes of trailer running. Any suggestions on any "sacrificial" cheap oil that I can use with no harm? Perhaps some cheap walmart oil and I could actually get 2-3 oil changes before I go back to aeroshell. (I would only be running it on trailer.)

I’d use 50 weight whatever for your purposes. It would be hard to do more damage.

You are gonna have to get the oil temp up to boil out the water. Try covering part of the cooler and get the oil to 200 F for a while.

I’d suggest dropping the pan to clean it out after you get her dried up.
Add 1 qt of transmission fluid to current oil, get it hot before you drain it off then run a oil change with 15w40 and 1 qt trans fluid, let it run till it gets hot, drain it while hot and blended, the detergent will allow it to mix in, run aeroshell after that.
Ok, I watched your videos, the rust on the valve springs will eventually cause them to break, I would highly suggest you pull all 6 cylinders, have them overhauled, may have to take them out to plus .015 if they aren't already, i bet cylinder bores are pitted,have springs replaced, put a set of 640518 pistons in it, have them machined for 2nd plug, get the pin and gear to drive a 2nd mag.
Thanks yall. I will do a temp oil change this weekend for sure. I like the transmission fluid idea.

John, I was worried about advice like yours.....good advice for sure.....but just consider me in denial! LOL Good news is that it's not my boat and I didn't pay anything for it. The bad news is that its not my boat and I put some dollars into it. Its a gamble for sure. The plan was that I would store it here at my place (out of the weather) and work on it a bit and my buddy was okay with me using it. So, plan is to try to get it up and running and get some use out of it, cut my teeth, etc. Hopefully that plan still happens and major repairs can wait.

Run it but just have in mind that the springs will eventually fail, not all at once but here and there, they are easy enough to change on engine with compressed air holding valves shut (STAY CLEAR OF PROP OR REMOVE IT) if you get it running good, enjoy! Seems you know enough to get you back to the landing, with a good tool and emergency parts kit on board, you will do fine.