Author Topic: bubbles in oil (Read 5265 times)

shrike · « **on:** July 27, 2007, 10:46:37 AM »

Hello,
I was looking at my oil yesterday right after I turned the engine off and there were some bubbles at the top of the oil. They disappear after a few minutes. Is this normal?
I know it's not good for the oil to foam but I was wondering if it is normal to have a few bubbles.
The oil level is to the F mark or just a bit above on a level surface with both wheels touching the ground and the engine warm or hot.

txbanditrydr · « **Reply #1 on:** July 27, 2007, 10:58:21 AM »

Everything you describe is normal to me - except for the fill level.. it's overfilled IMHO. Of course, you didn't mention whether that was noted on the centerstand or not. Also, oil will expand when heated so the level will register higher after warm-up but don't worry about the "little bubbles at the top". Oil that looks foamy throughout and milky-brown is a totally different story.

shrike · « **Reply #2 on:** July 27, 2007, 11:12:00 AM »

Thanks,
It was not on the centerstand. I was balancing it with one hand. When it's on the centerstand the oil is close to the empty mark.
So with two wheels on the ground the oil is to the F line. I thought that way of checking it was fine.

txbanditrydr · « **Reply #3 on:** July 27, 2007, 12:46:03 PM »

Quote from: "shrike"

Thanks,
So with two wheels on the ground the oil is to the F line. I thought that way of checking it was fine.

You are correct... but you still cited it was reading above the full mark. Had it been above the full mark on the centerstand then it would have been WAY overfilled. Just picking a few nits here and there.

shrike · « **Reply #4 on:** July 27, 2007, 12:58:29 PM »

Yes it is a bit over the F mark when warm with two wheels on the ground. I think it's about 2-3 mm over. I don't think I should bother taking it out. But if I got nothing to do tonight maybe.
Anyways i checked the draint ube from the airbox and it's fine, there's nothing in it.

So is it still raining a lot in Texas?

pmackie · « **Reply #5 on:** July 27, 2007, 12:58:35 PM »

Many of the engine parts "churn" air into the oil. Crankshaft, clutch, transmission, etc. so it IS normal for you to see bubbles coming to the surface as soon as you shut off the bike. I assume you are viewing through the site level window.

As TX said, oil that "holds" air, looking like a creamy emulsion is bad.

Just cause I'm in the mood, some additional oil info: (

watch out!!! Thread hijack coming!)

Virtually all oils contain some form of "foam" inhibitor. Since most mechanical equipment causes "entrained" air, as described above, oil would normally foam, looking like beer with a head on it. What oil manufacturers do is to add a surface tension modifier. You can't stop the bubbles from forming, due to air entrainment, but by reducing the surface tension, you can ensure the bubbles break quickly, reducing the foam. All is then good in the world... (there's a BUT coming...)

Foam inhiibitors can be impacted by contamination. The most common is that engine oils and certain industrial oils, like hydraulic fluids, tend to use different chemistries. It is common that mixing the two types of oils will nuetralize the foam inhibitor. Some are impacted my things like silicone, the most common causes being impacted by silicone sealant on reassembly, or too much airborn silica (dirt).

If you're seeing foam collection (too much head on the beer), you need to change the oil, as something is contaminating it.

On the other hand, air/oil emulsion (think about a milkshake) is a different problem, again caused by contamination. We have all likely seen the effect of mixing Glycol Antifreeze in your engine and whipping it up into a grey frothy mess!!

If you see an emulsion problem, you need to look further to find the source of the leak, as well as changing the oil.

That's todays oil lesson...we now return you to your regularly scheduled post!! (

Thank God...thread hijack over)

shrike · « **Reply #6 on:** July 27, 2007, 03:16:19 PM »

It wasn't a thread hijack. It was related to the subject and thanks a lot for the info.
I was asking this because I don't remember having seen those bubbles. Maybe I never checked the oil right after turning off the engine.
You said something that caught my attention. You said the additives that lower the surface tension can be neutralized.
I did my oil change a week ago and I switched from dino Rotella to synthetic Amsoil. So maybe this is causing it since some oil is leftover int he cooler and other parts of the engine. I was planning on keeping this oil for 5000 km before next oil change

pmackie · « **Reply #7 on:** July 27, 2007, 03:33:02 PM »

Generally all engine oils use the same type of additives and don't conflict.

If you are seeing a lot of "foam" accumulate on TOP of the oil (as oppossed to seeing bubbles IN the oil) or if oil is accumulating in the airbox, or visable when you pull the filler plug, then you may have a contamination problem.

Not likely though. I think you are just seeing the air bubbles coming out of the oil, a normal condition.

txbanditrydr · « **Reply #8 on:** July 27, 2007, 05:12:38 PM »

Quote from: "shrike"

I did my oil change a week ago and I switched from dino Rotella to synthetic Amsoil.

Must..... resist..... urge..... to..... start...... oil...... thread!!!!

Attention - step away from the keyboard.... put your wrists down and step away from the keyboard.

shrike · « **Reply #9 on:** July 27, 2007, 05:45:40 PM »

I should be fine then. I will check it from time to time but it should be normal.
I am planning on doing a few kilometers this week end so I wanted to make sure everything is fine.

I was afraid this is going to turn into an oil thread but until now we are safe:)