TOPIC:

After motor starts, oil fills cooler and level drops. After motor stops oil goes down from cooler. Maybe oil filters have valve and oil stays in cooler? I guess it is a good idea to keep oil at highest line.

Yes No extra for cooler. Stick to upper level mark.

Keep the oil in the mid to upper level in the sight glass when cold.
All the oil slowly drains back to the sump on shutdown.
There are no one way valves fitted.
Never overfill to compensate for a cooler or you will blow oil .
If the cooler has top mounted fittings the cooler will hold it's oil creating a small amount of extra oil capacity to the whole system.

That's the whole idea to my cooler. I can't have the fittings pointing up so I will have the lines come back up along the back bone tubes, then down to the fittings at the engine. I expect it to hold about 1/2 quart.
Steve

I asked this same question last month...and received the same answers.

I don't understand how adding extra oil will blow seals. More oil does not mean more oil pressure, it just means a higher oil level in the sump.

Two bikes: one with cooler and one without. Same oil level. With engine running the oil level in the sump will be lower on the cooler equipped bike. How is this good?

I went through that last time I had a cooler. It would all run back into the sump. I'd have dry starts until the cooler and lines would fill. I can see how the oil wouldn't get past the oil pump easily, but it would drain through the passages in the head. I hope to avoid this with my line routing. I had a extra quart in the bike then and did NOT blow any seals or have any in my air cleaner.
Steve

The aftermarket shunt type of cooler "taps off" a little oil from the high pressure output of the pump and sends it through the cooler and it returns to the bottom of the pan where it mixes with the oil going through the engine. The oil line fitting goes into the place where the oil pressure sending unit threads into.

According to the maker of the cooler (I talked to) they said you do add an extra quart of oil to fill the cooler and lines so the correct amount of oil is still in the engine.

Obviously, if the cooler came on the bike from the factory, the sight glass would be calibrated to read the correct level.

The PO of my bike decided to top the oil up before I came to buy it. It was blowing oil out through the breather and that helped me get a good deal on it. I asked him how much oil he put in "2 quarts" he replied, looking in through the filler you could see the oil level, it was so full. While diagnosing the problem he seemed amazed that there was a window there for oil level and asked me what it was for. Never did work out why he thought the oil needed topping up. I drained off at least 2 quarts of oil before even trying to run it, when I got it home, it still seemed a little high, based on tipping the bike and looking at the window, but I was going to change the oil anyway as soon as I got it running somewhere near, I didn't mess with it further. When I changed the oil I checked and how much came out and it was the best part of 5 quarts. Thankfully no harm was done. Putting too much oil in causes problems due to potential crankcase over pressure, not any increase in oil pressure, and it can cause gaskets and seals to get blown out as the volume of oil decreases the free air space in side the cases..

The PO of my bike was a super nice guy and thankfully he paid someone fairly reputable and knowledgeable to do all the maintenance and repair work every year, because if there was ever someone who should not have owned a classic bike it was him, he had no clue regarding any thing. Luckily he also only rode it about 1000 miles over he 10 years he owned it which reduced the possibilities for it getting destroyed. It's actually quite scary and why I spent a lot of time, in addition to my modifications going through everything on the bike for safety reasons before daring to ride it at any sort of speed.

If fitting a cooler it seems it would be a good idea to have top fittings to keep the oil in there for quicker circulation, the downside is you need to drain the cooler when you change the oil or you won't be able to get all the old stuff out.

Nessism wrote: I don't understand how adding extra oil will blow seals. More oil does not mean more oil pressure, it just means a higher oil level in the sump.

Blowing seals has NOT been mentioned, neither has oil pressure and more oil does not simply mean a higher oil level with no consequences.
The pumping action of the pistons and cylinder blow by etc creates crankcase pressure ( hence the need for a breather ) and an increase in oil volume equals a decrease in crankcase air volume which will result in elevated internal crankcase pressure and this will produce a higher risk of oil leaks
The crankshaft and other components, gears etc, will also be sat in an increased depth of oil which will then be churned up by their reciprocating mass allowing a denser volume of suspended oil particles in the pumped air .
This denser oil mist coupled with increased crankcase pressure will be blown and pushed passed the baffles in the breather and up into the airbox by the pumping action of the pistons.
This will find it's way in to the air box and through into the combustion chamber OR out of the engine to open air if no air box is fitted.
Depending on the amount of overfill the amount of oil mist and oil loss will vary .
On top of this the higher oil level will also increase drag on the crank affecting performance, over oiling of the cylinder bores by excessive splash and the resulting aeration of the oil can cause lubrication problems.
All this will have been taken into account at the engines design and development stage by the manufacturer hence the upper maximum oil level they have stated is there for a reason.

I understand of the consequence of extra oil in the sump. What you don't seem to acknowledge is that after oil fills the cooler, which drains down when the engine is turned off, the oil level in the sump will be LOWER when the engine is running. That's my point. The cooler results in a LOW oil level in the sump. To get back to a normal level the oil level in the sump when running a little extra oil in the system is needed.

It is very easy to check. Check oil level when engine is running. I think it should be seen in the glass. Maybe below "low" line but you have to see it.
Another question is checking oil level procedure. Different bikes have different procedures in owner's manual Some of them say to check cold engine, some say to start engine, stop it and wait 5 min.

Nessism wrote: I understand of the consequence of extra oil in the sump. What you don't seem to acknowledge is that after oil fills the cooler, which drains down when the engine is turned off, the oil level in the sump will be LOWER when the engine is running. That's my point. The cooler results in a LOW oil level in the sump. To get back to a normal level the oil level in the sump when running a little extra oil in the system is needed.

No extra oil is needed above the max level line when checked cold for the reasons I mentioned previously.
The oil level marks are for static oil level checks when cold NOT running or hot.
Unless you had ridiculously long cooler hoses and /or a stupidly oversize cooler matrix the oil capacity of the cooler system would never exceed the difference between the upper and lower limits of the engines workable oil level .
As long as the oil pickup is not exposed to air when running as would be indicated by the oil pressure gauge or light there will be no issues.
You are imagining a problem that doesn't exist under normal circumstances.