Hello, I’ve read a couple of threads with similar stories and, apparently, it’s moisture in the engine oil condensing and creating that “milky” mark on the oil level sight glass. Was hoping that someone could shine some light and explain the technical aspect of why it happens and how to prevent it. For info, it’s happened on a Hypermotard 821 - 2013. Thanks!
Not seen it as distinct as that before usually it’s a milky scum on the inside of the glass or a line across the top of the oil. Either way, as you say it’s just emulsified oil and water and will go when the engine gets up to full operating temp. The water comes from condensation forming in the engine crankcases, they’re not airtight, just think of the breather valve. Water condenses out of the air in minuscule amounts, these collect, get mixed with the oil and emulsify. Particularly prevalent if the bikes been standing for a while then is started but not used or allowed to get up to full operating temp. The oil needs to get to 100c (or as near as dammit) to boil off the water and separate the emulsion and get back to its full self. It won’t do any harm and will go when the bike is next rien long enough to get up to the correct working temp.
...however, if the water/oil emulsion doesn't disperse when the oil is up to working temperature (or higher, as WCP says) you may have coolant in there. I recommend warming it up fully - hoping that the water comes out of the emulsion - them dump the oil & filter and change for new. When you crack the drain plug, try to see if there's any water present as it'll be the first fluid to come out. Then you'll know...
Thank you both for your replies. That would make sense considering lately I’ve been using the bike to nip into town (~10 min ride). It has its yearly service due soon, so I’ll change the oil then and keep an eye out for any water. I’ve read some suggestions which recommend removing the filler cap after a long ride to allow the engine to *breathe* and the condensation to find its way out. Thoughts on this?
Ive not heard if that, seems a bit of a faff to me snd will definitely be a faff on any bike wrapped in bodywork. I’d be more inclined to take the long way home and up the ride time to 20-30 mins. Anyway, don’t sweat it, it’s no big deal (unless as @Keith_P says but you’ll know that soon enough anyway) it happens on all bikes with sight glasses which are used only for very short runs and the amount of water in there will be minuscule it just looks worse than it is.
Are you doing a lot of short journeys, this can cause this to happen. Take the bike on a long ride, get the engine hot and hopefully this will clear. If not change the oil and keep an eye on it, also mark the coolant level and see if it is dropping. Usually internal coolant leaks will result in overheating.
Not a bad idea to remove filler cap if you do several short runs. Here’s some mayo from my cars filler cap which is generally used for journeys of a couple of miles. It’s worse in winter.
" They all do that mate " .... but seriously .... that glass is probably the coolest surface that the oil comes into contact with so it's not surprising to see some condensate there .
Yes, it does help. I used to do it with the air-cooled 900SS I used to own. If you try this leave the filler cap somewhere obvious, like on top of the seat or fuel filler, so that you won't forget to refit before your next ride, or a few miles down the road you'll have a very oily right boot.
This guy is very knowledgeable regarding Ducati, pretty simple solution when you think about it, https://www.instagram.com/p/CETxguoB8Xg/?igshid=s2fa35x8vwq2
Simple solution to the problem is plan a nice 50 mile or so route on roads where you can keep up a steady pace, say 50 to 60 mph or more if legal and safe to do so. Then the fun bit you got to keep the revs at 6K or above so plenty of use for the lower to mid gears. Basically you have to generate a higher level of heat in the engine and the moisture will get blown out. So a nice spirited (but safe) ride for 50 miles every now and again and also avoid the 10 minute nip into town when there is a perfectly adequate 30 minute plus route available.