I've read a lot of people say to run engine oil 1/2 qt. or so less than full to help mitigate oil blow by/carry over(whatever you wanna call it, oil comming out head vents and out of the air filter). Can anyone explain how running low oil in a dry sump system helps with the blow by problem. Its my understanding that the blow by in the 88" is because the oil doesn't return to the bottom end fast enough to be scavenged by the pump and returned to the resivoir, or the pump is insufficient to scavenge fast enough to return to the pan. Any insight would be greatly appreciated.

 

People do that usually after they have ovefilled their bike gotten soaked with oil and are over reacting. Or they are simply too stupid to read a dipstick or follow the simple oil check procedure specified for their bike. I run my bike full and never a problem. Just follow the simple instructions for checking oil hot.

 

There are two oil pumps in a Harley stacked side by side. The return side is approximate 10% larger the then the pressure side that lubricates the engine. Therefore there can never be too much oil in the engine and even if you filled the reservoir to the top and poured some inside the engine it would not stay in engine and would push out the dip stick. What you are seeing is just the one-way vent valves letting enough oil come thru plus the mist setting and running together. With a factory sealed back plate on the air filter it will catch and hold it better then these open back systems. My bike has very little at below 3000 rpm but as soon as I get over 3000 for say 10 miles I will see it. Let it sit for two - three weeks and start it and drive 10 miles and park it and I will actually get a few drips on valve lifter covers.
Do not fall for these people saying run oil low. Harleys only have so much oil in them and even cutting your oil by 1/2 a dipstick reduces your cooling some how be it very little but I fill you need all the cooling you can get and running the oil level at top of dip stick does not affect blow by and I guarantee they are going to be many who blow me away for saying this.
That being said after draining oil and replacing it and the filter (I only do filter ever other time) I put oil up to about 1/2 way on stick and start engine. Check for leaks at drain and filter and shut it off. Add oil to approximate 1/2 way on stick. Get my bike to about 180-200F on dip stick and top off to full with bike level and not on stand. Some newer bike may say on stand so you need to read manual here. I can only assume if your manual says to check it on the stand that Harley's Engineers have adjusted the dipstick for this application.

 

Not me I agree 100%

 

Hey thanks y'all. That was my assumption that filling to the correct oil level would not cause the blow by. Running above 3K rpm seems to be about where I am seeing it most also. Thanks again

 

TC engines when run for several hours at constant freeway speeds will experience some blow by and sometimes drip out the air cleaner. This is common. Nothing is wrong. Some guys will put a stayfree mini pad inside the football cover between the filter and cover to absorb the oil when on long trips. Others will build a custon blowby system with a t-fitting that is run into a collection cup or to drip out below the frame.

 

Back when I was running the football cover that is what I did. Mine just need the light day. Stuck right there heat and all and I never had a drip. Now I just run the Skull cover over the end of the stage 2 filter and I thought it might look a little weird stuck on the bottom of it.

 

I couldn't help but notice that not one of the naysayers have an "A" motor.

Go ask your question again in the touring section. You might be surprised what you hear.

 

Just rode 350 miles averaging 70mph stopping twice (once for gas and second to rest my butt). Complete oil, filter and Primary change the week before. Got back in town and checked the oil level when I shut down after almost 5 hours of running. Oil level was slightly above full mark, maybe .200 above. No leaks, or drips around oil/air filters, jugs or heads. Oil looked virtually the same as when I put it in about 600 miles before. I inadvertently added to much oil when filling thus the extra .200 over full mark. My point is, filling at or above the full mark does not necessarily create oil blow by otherwise I would have encountered. I did however encounter numerous bug strikes and water spots all over my bike and my face, but that was due in apart to mother nature and my poor selection of departure time. Did I tell you my butt is still sore too? My next plan is to switch seats before long runs...

 

Speaking Evo only here:

Running the oil full in a (EVO) Softail oil tank causes blow by because when the oil level is too high it covers the breather and oil return tube openings in the tank.

This makes it difficult for oil to return to the tank, so it blows out the breather. Running 2-1/2 quarts in an Evo Softail won`t hurt a thing and will reduce the amount of oil blown out of the breather. Running hot is not a problem with an Evo engine.