Rage

I use rhe Redline shock Proof drive oil and only need a few gallons/year of the Amsoil 20W50. After shipping and the membership cost I might as well just pay the same money and get the Mobil1 V Twin oil. So my inquiry still stands.

sleeper_dave

So I got an oil analysis back yesterday. 3.3% fuel. This oil was in the boat for storage over the winter, but only had about 11 hours of run time. Wear was a little higher than normal, but the big problem is the fuel.

Should I be worried, considering this oil sat all winter?

What the hell would cause so damn much fuel to get in the oil? Where does it come from? I just did a complete tune-up and rebuilt the carb. Motor is stock. Jets in carb are stock. Everything is stock. Plugs look fine after running at idle. Is there something i'm missing?

zahndok

Possibilities might include:
too rich (Carb) (But your plugs look Good so probably not)
rings, (lots of blowby).
Do you run a blower?
Carb flooding when sitting leaking fuel. (float)

sleeper_dave

Too rich was my initial thought. But stock motor, stock jets, fresh carb rebuild (although that wasn't until spring), and the plugs look good so i don't think it's too rich.

rings are a possibility, but the motor only has 140 hours on it since a rebuild. There is definitely some blowby, but i'm not sure if it's a lot for a marine BBC, i'm thinking these motors are put together fairly loose because they're run so hard.

no blower

carb flooding while sitting or leaking fuel into the intake would explain the high reading over the winter. There didn't seem to be any obvious problems when i pulled it off in the spring to rebuild it though. If the fuel goes away next sample i guess that points to the carb.

How much fuel in the oil is normal? Any at all?

minxguy

One of the issues is the oil was "used" and there was never an oil analysis before storage, so you don't know if the oil was contaminated before storage or during storage. (Point for changing oil before storage).
You may have had some "washdown" from the fuel weeping by the rings during storage and taking the oil with it. This may lead to some surface rusting of the "washed" sections of cylinder bore and perhaps the corosponding area of the rings.
Do you have an oil temp gauge? if you do, how hot is the oil getting? If the oil is too cool the contamination won't burn off. It will just build up in the oil.
When you change your oil, you should keep a retained sample of the new oil you are pouring into the motor and when you do you next oil analysis send in both the new retained sample and a sample of the used oil. Why? The retained sample will give you a base line of the oil that you can compare to the used sample. I think you would want to know how YOUR oil held up and not compared to X number of other brands.
Next time you store the boat, turn the gas off and run the carb dry. At least you will eliminate the fuel draining from the carb issue.

Ken

sleeper_dave

I did change the oil before storage. changed it in the water and ran the boat probably 10 minutes at idle to get to the launch ramp and haul it out. Then I put about 11 hours on it in the spring before the oil change. The sample I took when changing the oil before storage showed 0.8% fuel.

I do have an oil temp gauge. The oil wasn't getting very hot at all last season, especially near the beginning and end of the season when the water was cold. I've since added an oil thermostat, now I see steady 180°-200° oil temps when running.

Is some fuel in the oil normal with a carb'd boat motor? How much should I be worried about? Blackstone says <3.0% is what it "should be" but i'm thinking 3% is pretty high.

ActiveFun

Hydro,
Do you still recommend the 15/50 EP gold cap for a pleasure boater with stock HP500 carb motors that runs pretty hard?? or is the silver cap 15/50 good enough?? The gold cap is much harder to get. The motors have almost 300 hours on them.

minxguy

Typicaly less than 1% would be more normal. So .8% is excellent very typical. Glad you did the analysis before storage? Now you have a better idea of what caused the elevated numbers.
Not to say you do not know what you are doing, but is the rebuild up to spec? Float level, bad needle and seat? Piece of dirt stuck in the seat for the needle? Choke sticking?
Ken

sleeper_dave

When it comes to carburetors I would be one of the first to say I don't know what I'm doing! But seriously, I followed the instructions in the clymers manual to the tee. There were only a few adjustments, float level and drop, choke pull off, and one other thing, and I was pretty confident that I did everything correctly. The float level should be fine, unless the specs in the clymers manual are inaccurate. The old needle valves and seats looked good, but I did replace them. The rebuild kit for the weber carbs is pretty complete... for $100 it should be! I even put the floats in a pan of fuel and verified that they float before reassembling the carb.

Two more questions, a little more generic... is it "normal" to burn some oil? I don't burn any when cruising around normally, but when I open it up it burns a bit.

Also, what are "normal" numbers to see for a marine engine on a blackstone labs test report? My report says "elevated" or "slightly elevated" wear in a few categories. Does that mean more than a typical marine engine, or more than a typical modern car engine? I would expect more wear than a car engine to be the norm for a marine engine.

minxguy

In theory, engines shouldn't burn any oil, but in the real world some do. what's acceptable? That depends on who you talk to. I would imagine if you can see the oil smoke out the tail pipes thats not acceptable. Spek to service guys at car dealers they will probably say 1 qt/1000 miles is ok.
If you are seeing oil consumption and higer speeds it is oil getting past the rings. Higher speed=higher oil temps=thinner oil=more consumption. Fuel dilution doesn't help at all.
Ken