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Premium Member
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Discussion Starter #1
Question / Short Story:
I just started my bike after 5 months of "cold storage" in the shed. It started right up and after idling a couple of minutes I got a low oil pressure warning lamp and shut the engine off. I checked the oil level in the sight glass. The level was OK, but the oil appeared whitish. Upon further checking it turned out to be air entrainment in the oil ( full of small, < 1 mm, air bubbles) which cleared up after 20 minutes or so. Has anyone else seen this on a "cold" engine?

Longer Story:
Last fall, I changed oil using Motul 3000 10W-40 and rode about 10 mi to distribute the oil before storing in the shed.
I was initially concerned about a coolant leak into the oil. I started it up again and rode to my garage (about 100 yards) where I could work on it. I was afraid to run it too much. Same result - the sight glass showed white oil. Again it cleared up after 10 - 20 minutes.
I borrowed a coolant system pressure tester from Advance Auto (quite a professional kit by the way) and confirmed there was no coolant leak - whew:)
I started and ran the engine for about 30 sec and again confirmed white oil. I drained it immediately and all the oil was the same condition - whitish - that eventually cleared. After internet research, I learned that oil "foaming" is lots of bubbles that cling together on the surface of the oil. "Air entrainment" is lots of tiny bubbles (<1 mm) distributed throughout the oil. This is my symptom.
This is the first I have used Motul 3000 so I changed the oil using Rotella T 15W-40. Same result - air entrainment.
In the past I have never looked at the oil sight glass on a "cold" engine. Perhaps it has always been this way and will be OK after a ride. I did idle until the coolant was up to temp, but I knowthat the oil was still not up to temp. Despite my concerns, I plan to go for a short ride tomorrow and take another look at the oil.
Has anyone else observed this?

Note: The initial "low pressure warning lamp" was probably caused by a low idle because I took off the choke too soon.
 

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Linkmeister Supreme
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7,960 Posts
Never heard of "air entrainment" before. Thanks for the education.

Enjoy the ride and hope the symptoms clear up by the time you return.
 

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Super Moderator
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11,934 Posts
Question / Short Story:
I just started my bike after 5 months of "cold storage" in the shed. It started right up and after idling a couple of minutes I got a low oil pressure warning lamp and shut the engine off. I checked the oil level in the sight glass. The level was OK, but the oil appeared whitish. Upon further checking it turned out to be air entrainment in the oil ( full of small, < 1 mm, air bubbles) which cleared up after 20 minutes or so. Has anyone else seen this on a "cold" engine?
.

Yes...my S2 (Kaw 350 two stroke triple) did this one winter. the oil looked like mayonaise.

My answer was to change the oil ASAP. Some of that white crap is water from condensation. A new batch of 10w 40 with a longer warmup time solved the problem for the rest of the winter.


KM
 

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Premium Member
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117 Posts
Discussion Starter #4
All is well. My oil was not contaminated with coolant or water. It turns out that it is normal for tiny bubbles (air entrainment) to occur initially especially in cold, high viscosity oil due to turbulence caused by oil pump / gears / chains / filter. I had just never turned the engine off before it warmed up and checked the oil in the sight glass before this.
Yesterday I went for a 5 mi ride and the oil looked normal after I returned. This morning I turned the engine off about 2 minutes after startup (~40 degrees) and again it was milky white - and very slow to drain back to the crankcase. Rode 10 mi and again the oil looked normal. (Now running with Rotella T 15W40).
For further confirmation, I checked for this condition on my Concours 14 which has Rotella T6 5W40 Synthetic. After running about 2 minutes (from initial ~ 40 degrees) there were lots of tiny bubbles in the oil visible in the sight glass, although not nearly as much as the VN750. I ran the same check with my pickup truck which has Shell 5W30 and noticed a few air bubbles on the dipstick.
Perhaps this is common knowledge for many, but it was new info to me (after all these years - who knew). So if your oil looks white after you shutdown a cold engine - don't worry. Go for a ride and see if it clears up.

This experience for me also re-enforces the importance of using low viscosity oil in cold weather and letting the oil warm up before high load or revs. (Note: idling does not really warm up to oil very well, even if the coolant temp is up. You need to 'gently' ride for a few mlles.)
 
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