Oil not returning to crankcase

[Big T]

Background - I've owned my 78 1000 since new and have done all the maintenance since the warranty ran out.
Last summer, it started leaking oil at the base of the cylinder, not much, just messy.
I put the bike up for the winter in November and took it out and started it a few weeks ago. After running it a few minutes, I shut it down and waited a while to check the oil. After an hour, the sight glass showed no oil.
I thought, I can't believe I let it get that low, so I added over a pint of oil with no visible change.
So, I thought, if my oil is that low, I'd better change it. So, since Rotella T6 isn't available, I picked up some Ecstar and a new filter.
Only about 1 1/2 quarts drained out. I was still puzzled where over a quart of oil went.
I filled it with the Ecstar, at 3 quarts I could see it in the sight glass, brought the level up to mid glass and fired up the bike.
Let it run til warm and shut it off.
After 10 minutes, no oil showing in the sight glass.
I pulled out the FSM and checked, oil just runs back down into the crankcase from various parts of the motor.
The only place in the motor that can hold much oil is the cylinder head.
So, where's the oil ?
And why isn't it flowing back down?

[rphillips]

This is gonn'a be interesting, never heard of them returns being anywhere near stopped up on a GS. Years past Quaker State oil would stop up some of the returns on a V-8, but never saw a GS in that shape.

[Nessism]

Three quarts isn't enough. It takes close to four to fill the engine if changing the filter.

[bwringer]

Quite a lot of oil pools in the 8V heads by design. Once in a while someone pulls a valve cover and gets panicked when they see all the oil just hanging around on top of the buckets and such.

But it falls back down via the center tunnel (don't see how in the world that could get blocked enough to retain a significant amount of oil), and through the passages at the front corners. And there are passages in each shim bucket bore that dump into the center tunnel. There's a lot of space around the corner head studs, and these passages are quite large.

There's just no mechanism aside from being infested by wasps or hamsters for all these very large passages in these engines to get blocked.

All in all, I suspect the bike was initially a lot lower on oil than you thought (so maybe put fixing the leak a little higher on your priority list). You might have also underestimated the amount of oil that came out. And, as Nessism remarked, you need more than three quarts to top up.

[rphillips]

When it was first started with the 1 1/2 qt. did you see the "OIL" light was on? After filling it to center of sight glass (near 4 qt.) & running it, what did the "OIL" light do?

[Big T]

The initial start up of the Rotella, the oil light went out on a few seconds, which is normal after sitting for 4 months. The next start up, it flickered, which started me down this path
as to the 3 quarts, go back and read what I wrote. The Ecstar jug, just like Rotella, has the graduated strip down the back.

The oil light goes off immediately with the current level of Ecstar

[Rijko]

I have seen something like that with an oil cooler ?

[Cipher]

Are you doing this on centre stand or side? Try it on the centre with the motor at operating temperature
On the side a measurable and largish volume of oil stay in the head
also whilst on the stand the oil at the sight glass is highest point it reaches in the sump. even a slightly unlevel floor can cause a large difference.

[Burque73]

This disappearing oil thing sounds familiar. Another member (Noreg?) had the same issue a while back. I don't recall what the outcome was though.

[Buffalo Bill]

I thought maybe the problem would disappear on April 2nd?

[Big T]

Update:

Being old, I got an actual FSM from Ed last year. Because, one starts to forget Then, trusting the comments, and consulting said manual, which said 4 qts with filter change, I went from 3 1/2 qts to just under 4, using the graduations on the jug.
Oil level appeared in the sight guage, ran the motor for a few minutes, oil level in the sight guage was good.
Went for 100 mile ride yesterday, all is good

The April's Fool joke was on me

[Pete Wrigley]

Have similar issue. I changed out my oil pan gasket, changed filter while I was in there. Added 4Q of Valvoline 4-Stroke Motorcycle Oil. I did not start it (pipes are off and no fuel) but I did crank motor to get pressure. Since then the oil level in the glass appears empty. I know there are 4Q's in that engine as nothing leaked out.

Do I need to run the engine and have it fully circulate?

[rphillips]

No Pete, just take it off the side stand & put it on the center stand.

[Pete Wrigley]

No Pete, just take it off the side stand & put it on the center stand.

It took a few days (not running) but the oil did slowly return to the full level.