Checking of Oil Level

Stevie4scoops

Well-known member
UKGSer Subscriber
Joined
Jul 14, 2014
Messages
4,047
Reaction score
12
Location
Gloucestershire UK
My KTM manuals say to check the oil level on my various KTMs when the engines are at operating temperature and have been switched off for around a minute.


Can anyone explain why the level is substantially different when it's hot than cold. I can understand a small difference due to the oil expanding when hot but not the amount it does.


For example, when the engine's cold and the bike's on level ground there's no oil showing in the sight glass but when it's hot it's at the top.


My GS was always consistent whether hot or cold so it can't be that oil expands by 25% when heated from 20 - 80C


Any thoughts to explain this?
 
I know the answer to this and here's the explanation:

Your bike has blown a head gasket. The water mixes with the oil when it's running so you see a coloured fluid in the window. When the bike is stationary the water separates out, so you still see a fluid in the window, but because its water you can't see it.

Best book it in before the engine blows :comfort
 
I know the answer to this and here's the explanation:

Your bike has blown a head gasket. The water mixes with the oil when it's running so you see a coloured fluid in the window. When the bike is stationary the water separates out, so you still see a fluid in the window, but because its water you can't see it.

Best book it in before the engine blows :comfort

Thanks for your explanation but I'm pleased to report that this is the case on several bikes I own and run and none of them have blown their head gasket.


It happens on all my KTM and Husqvarna bikes
 
My KTM manuals say to check the oil level on my various KTMs when the engines are at operating temperature and have been switched off for around a minute.


Can anyone explain why the level is substantially different when it's hot than cold. I can understand a small difference due to the oil expanding when hot but not the amount it does.


For example, when the engine's cold and the bike's on level ground there's no oil showing in the sight glass but when it's hot it's at the top.


My GS was always consistent whether hot or cold so it can't be that oil expands by 25% when heated from 20 - 80C


Any thoughts to explain this?

When the oil is hot its viscosity is much higher and thus it flows more readily, thereby showing a higher level. Both my KTM's RFS & LC8 show much lower oil levels when cold.
Don't fret about the level when it is cold, the crucial thing is that you have the correct oil level at normal operating temperature.
 
When the oil is hot its viscosity is much higher and thus it flows more readily, thereby showing a higher level. Both my KTM's RFS & LC8 show much lower oil levels when cold.
Don't fret about the level when it is cold, the crucial thing is that you have the correct oil level at normal operating temperature.

Thanks, I’m not concerned about it but curious as to why it happens.

I know oil is much thinner when warm but this doesn’t explain why it’s higher up the sight glass when it hot.

If the engine is at operating temperature and switched off, the oil flows to the bottom of the engine and shows at the higher point on the site glass.

When it cools down, it disappears from the site glass altogether as if the level is very low.

What I cannot understand is why does it show a high level when warm and very low when cold?

Oil is very thin these days and even more so when hot so I would expect it to run to the bottom of the engine very soon after being switched off.

Where does it go when cold to show such a much lower level?

Bloody mystery to me
 
I’m with you on this.

Is there a ‘seperate’ oil tank. Part of the engine block but seperate (so they are in effect a dry sump)?
My LC8 is like that but the oil sight glass (tube) in in the ‘oil tank’ which is a compartment at the front of the block.

Andres
 
I’m with you on this.

Is there a ‘seperate’ oil tank. Part of the engine block but seperate (so they are in effect a dry sump)?
My LC8 is like that but the oil sight glass (tube) in in the ‘oil tank’ which is a compartment at the front of the block.

Andres

Thanks but not on the single cylinder and 790 Dukes
 
Thanks, I’m not concerned about it but curious as to why it happens.

I know oil is much thinner when warm but this doesn’t explain why it’s higher up the sight glass when it hot.

If the engine is at operating temperature and switched off, the oil flows to the bottom of the engine and shows at the higher point on the site glass.

When it cools down, it disappears from the site glass altogether as if the level is very low.

What I cannot understand is why does it show a high level when warm and very low when cold?

Oil is very thin these days and even more so when hot so I would expect it to run to the bottom of the engine very soon after being switched off.

Where does it go when cold to show such a much lower level?

Bloody mystery to me

Simple physics, hot oil has greater volume than cold oil!
 
I also thought the LC8 was dry sump ?
I,over filled mine once , not paying attention to checking it at the right temperature.
 
When the oil is hot its viscosity is much higher and thus it flows more readily, thereby showing a higher level. Both my KTM's RFS & LC8 show much lower oil levels when cold.
Don't fret about the level when it is cold, the crucial thing is that you have the correct oil level at normal operating temperature.

The viscosity has nothing to do with it. JJH
 
Dry sump....oil needs to be circulated before any meanin full level can be seen.....simples
 


Back
Top Bottom