Disappearing Oil

[GOFAR]

Why does the oil level in my 2002 R1150 GS go down 8oz or more as the engine cools? It's driving me crazy! I thoroughly warm up the engine. Shut if off. Leave it on the sidestand for 5 minutes. Put it on the centerstand and wait 10 minutes. Check the sightglass. Oil is right at the center dot. Don't touch the bike for a day or two. Check the sightglass again. Oil is now down almost to the bottom of the sightglass! Where does the oil go? Is there air pressure somewhere that pushes it up into the cooler?

One has to be very careful, because if you add oil when it's cold and reading this false low, then when you next check it hot, the oil will be up at the top of the sightglass - i.e. overfilled and it will burn off.

Is there a cure for this annoyance?

Where is the heat actuated valve that opens so as to let oil get up through the cooler once the engine warms up?

[Mr. Frank]

Oil expands when it is hot, although mine only falls about a quarter inch when cool.

[gcsitts]

The delivery tech did caution me to add oil slowly when it is needed, that it doesn't take much to fill from bottom to top of the sight glass. I've noticed the hot-to-cold change too. It's much more dramatic than my other Beemers. (Since I only have 500 miles on this bike, I haven't actually had to add any yet.)

[Andy VH]

I think some oil gets trapped in the oil cooler which is high in the system. It doesn't always happen possible because of the position of the oil pump when the engine is turned off. The pump element can act as a bit of a seal and actually trap some oil above the sump when the engine is off.

[PGlaves]

Oilhead bikes are a bit hard to check the oil - because sometimes oil gets trapped in the cooler.

But the main reason oil that is at the dot fully warmed up appears lower in the window when cold is that the cold oil contracts and takes up less space.

I fill oilhead bikes to the center dot cold. On the centerstand - add 1st 3 quarts, then watch sight glass and fill to the dot. Hot, it will show above the dot. But that is not overfilled as far as I'm concerned.

Repeat at next oil change. If you have a "burner" or "leaker" you may need to add oil between changes.

[BONEY]

Heck, I just put mine on the side stand. If I see oil, I go.