Oil being thinned by fuel?

[Wing--Man]

Viable answers only please. I have no interest in immature, sarcastic and pointless rhetoric.

Is it possible for fuel to get into the crankcase other than intake to cylinders then past the rings?
My issue is the oil is only lasting 1500 to 2000 miles.
I have used 4 different manufactures of oil and synthetics, eliminating that possibility.
It is still clear like new but the shifting is like the oil is worn out and dirty which creates quite a drag while shifting gears.

At startup there is not a hint of a hydro-locked cylinder.

The coolant and oil are not mixing nor does the oil smell like gas.
But that fuel smell may not be present since it is likely to be evaporated off during use.

I disassembled and checked the petcocks fuel shutoff diaphragm, no hole.

I am not a Harley gear masher but a light or easy gear shifter.
I shift softly and feel the internal parts as they mesh. (And yes, I do sometimes get the Gear Dogs buzzing)
New oil it is silky smooth, as it gets old and used, more toe pressure is needed for both up-shift and down.
I do not want the early 1500s 4th gear issue, tho it is "supposed to have been" remedied. I have read some post 1997 Gl1500 owners have this issue.

What else... New to me last year 2000SE at 18,000 miles, always garage kept, clock now shows 50,000.

Ideas or thoughts appreciated.

[MikeB]

The coolant and oil are not mixing nor does the oil smell like gas.

IF there is fuel in the gas, you will smell it. The fuel odor will not dissipate out of the oil.

If you believe the oil is failing, have the oil analyzed. https://www.bobistheoilguy.com/engine-oil-analysis/

[2003Cobra]

To answer your question yes fuel can get into the crankcase. Normally you will see a rise on the oil dip stick if fuel is getting in there, although if it is a daily driver and it isn't sipping that much you may have a hard time telling but the issue is that if fuel is getting in there it is cutting the lubrication quality of the oil and hens putting more wear on the engine. The most probable cause it a stuck float or dirt holding a needle valve open. You will need to pull the carbs and remove the float bowls to check this. I have also seen a aftermarket fuel pump put out to much pressure and cause this as well but then engine also ran poorly due to flooding. Hope this gave you some insight and Good luck finding the cause.

[WingAdmin]

To answer your question yes fuel can get into the crankcase. Normally you will see a rise on the oil dip stick if fuel is getting in there, although if it is a daily driver and it isn't sipping that much you may have a hard time telling but the issue is that if fuel is getting in there it is cutting the lubrication quality of the oil and hens putting more wear on the engine. The most probable cause it a stuck float or dirt holding a needle valve open. You will need to pull the carbs and remove the float bowls to check this. I have also seen a aftermarket fuel pump put out to much pressure and cause this as well but then engine also ran poorly due to flooding. Hope this gave you some insight and Good luck finding the cause.

Except...he asked:

Is it possible for fuel to get into the crankcase other than intake to cylinders then past the rings?

So if you rule out leaking through carbs and into the cylinders, then no, there is no other way for fuel to make its way into the crankcase.

[MikeB]

Is there any evidence other than 'seat of the pants' diagnosis that the oil is losing its properties?
The only other contaminate I can think of is clutch fluid leaking into the oil and causing problems.
How is your clutch fluid level?
If it is clutch fluid, you face certain engine bearing failure.
Have the oil analyzed if you believe the oil is being contaminated or degraded.

[Elmobile]

You may also want to check the level in your clutch master cylinder. Small amount of DOT 4 fluid can drip in your transmission if the O ring in the slave clutch cylinder starts to fail. It is a known cause of failure which can have nasty consequences for your transmission...
Cheers.

[Wing--Man]

Clutch level never changes, forgot to add that to the main post. GOOD CATCH.

Tho the bike does run rich, just might be a high float.
I know that if there is a rich mixture the extra droplets do slide past the rings.
Since the oil goes bad slowly that is a high possibility.