Anti-foam additives

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Noticed some foam on top of the oil in the sight glass in my bike.

Keeping the air in the oil is bad for lubrication so I'd like to know if this is how these additives work?

I put this in the car section because I thought more people would see it.
 
Silicone is the additive used in a finished oil to keep foam at bay. There are base oil choices that can deal with the aeration of the oil better vs. others. Some motorcycle oils are formulated and tend to have more stable foam control- this due to the high RPM of the engines and the nature of riding.

Here is a great article on oil foaming: http://www.machinerylubrication.com/Read/255/oil-foam
 
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Thanks for the link. I thought the same thing about motorcycle oil that's why it surprised me when I saw it.
I guess foam on top is better than air in the oil.
 
What exactly is your question about anti-foam additives? From your post, I think you are asking if the additives are designed to entrain the air in the bulk oil so it doesn't form foam on the surface. If that is your question, the answer is no. Anti-foam additives are designed to weaken the surface tension of the fluid so the air bubbles easily and quickly break preventing accumulation of a head of foam on the surface.

If you are getting excessive air entrainment, that is often a mechanical problem of too much turbulence or churning of the oil. It is possible the oil may contribute by not dissipating the air quickly enough, but if you are using too high of a viscosity or the oil level isn't correct, it is not a deficiency of the oil causing the problem.
 
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Yes, I was thinking if the foam is on top the oil was doing its job and that's how anti-foam additive work.

The bubbles are gone within a minute so I guess it's not a big deal.

The oil was Brad Penn 10/40 MC oil in a TL 1000 FWIW. Thanks again for the info.
 
Right then, sounds like you are good to go. You shouldn't need to worry if it dissipates that quickly.
 
The gears will cause some surface bubbles. Foaming is when the oil will have air throughout the whole fill.

Foam

92073d1308883295-green-foamy-oil-img_1089.jpg


Not foam

viBEvAh.jpg
 
Those pics are perfect for the question I had. My oil looks the second pic.... maybe just a tad more bubbles but they don't stay long at all.
 
Originally Posted By: Kira
Do all bike engines have sight glasses?

All the ones I've owned have had them. I do like it, but I wouldn't mind a dipstick as well. Having to level the bike (can't use the side kickstand), and where they are located (often behind the footpeg and behind the rear brake lever) makes it kind of annoying in my opinion to check the level. But it's not so bad.
 
Originally Posted By: MotoTribologist
Originally Posted By: Kira
Do all bike engines have sight glasses?

All the ones I've owned have had them. I do like it, but I wouldn't mind a dipstick as well. Having to level the bike (can't use the side kickstand), and where they are located (often behind the footpeg and behind the rear brake lever) makes it kind of annoying in my opinion to check the level. But it's not so bad.

I expect most or all bikes need to be level to check the oil (else suspension changes would throw off the reading). I've only had one bike with a dipstick (on the left), but the centerstand was a dealer added option (which I got). Tall bike, so it might not easy to check while sitting on the bike. Maybe that's how people do it with dipstick-equipped cruisers? Don't remember how I checked mine before I got the centerstand installed.

I think the centerstand was an option also on the only bike I've had with the sight glass on the left. Holding the bike up by hand from the left to check oil isn't as secure as holding it up from the right, since in that case the side stand will catch it if you let it get away from you.

The bikes I've had with the sight glass on the right were pretty easy, centerstand or no.
 
Harley's and some yamaha's use dipstick's to check their oil. I wouldn't worry about a small amount of foam on the top of your oil, as the oil is drawn from the bottom of the oil sump. As long as your using the type oil that the mfgr recommends, you should be fine.,,
 
when I first got my yamaha xt660 I could see oil foam when checking the level.

Foaming is an unwanted property which put air buble and hinders oil's lubrication properties.

At the first oil change (600miles) I wiched to full synthetic and have not had any trace of foaming ever since.

What is an acceptable level of foaming? For me, none. MAybe it is worth you changing your oil at the next service
 
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