Does oil expand when hot?

[GuzziMoto]

189 ml is a fair amount. I have always checked my oil levels hot. Always have, probably always will. Every manual I've read has said to check level hot. Even my mother checks her level hot(not sure what that means). But I do think consistency is the most important thing here. I don't think your motor will blow up because you checked your oil at the wrong temp. But checking it the same way every time will help you spot changes that may need to be addressed.

[belfastguzzi]

My oil expands out through the casing when hot. Why?

 

[Guest ratchethack]

OMG, NO! I'm not done yet! More calculations!

 

So exactly how much of a change on the dipstick is represented by a change in oil temp of 60°F to 180°F?

 

(see previous calculations in my last post above)

 

189 ml = 189,000 cubic mm (mm^3).

 

A change in oil height in the V11 sump of 1 mm = 46,100 mm^3.

 

So 189 ml oil makes a 4mm vertical change in oil level.

 

On the dipstick, which is exactly 45° to horizontal, this translates to ~5.67 mm on the shaft of the dipstick.

 

QUESTION: Is this SIGNIFICANT?

 

ANSWER #1: It COULD BE if you measure oil level at different times at oil temp differences of 120°F.

 

ANSWER #2: It COULD BE if you did an oil change, filled the sump to max level COLD (the max level above which excess is blown out through the breather and condenser) -- and then go out for a long, hard & fast flog. In this scenario, you could blow out 189 ml of excess oil thru the airbox or condensor overflow (or what-have-you)!

 

ANSWER #3: It COULD BE if you top your oil level off HOT (by pre-heating the added oil to 180°F ), fill the sump to the min level HOT (the min level you know to be approaching the point where your non-Roper plate equipped V11 will expose its sump pickup on acceleration), then ALLOW THE MOTOR TO COOL TO 60°F, and then go out for a hard & fast flog before the oil has a chance to warm up. In this senario, you could be exposing those con rod big end bearing shells to oil starvation!

 

As for me, I'll continue to measure oil level cold. IMHO, especially with Roper plate installed (but I expect for most riders in most "normal" conditions, even without), oil volume expansion with heat is both practically and safely considered negligible.

 

BAA, TJM, & YMMV.

 

John, thanks for posing the Q. It was a job needed doin', and SOMEBODY had to be fool enough to do it.

[Guzzi2Go]

OK, did a search. Enquiring mind. Just HAD TO . . .

Er..., actually you DID NOT!

Had to search I mean...

 

The info matress provided contains all that is necessary to do the calculation. Here the results:

So, the difference in volumes at 20 (room temperature) and 80 (almost boiling) degrees °C is 0.15 litres. That'd be ~5 oz US or ~5.2oz UK for metrically impaired (or is it challenged? ) Or 5 shots, 3.4 jiggers, very few hogsheads (5*10E-4), roughly one UK gill, or 0.0009 barrels for you oil tycoons.

 

About what's significant or not, mumm's the word. I learned "significant" has different meanings in different cultures.

 

P.S.

I am still working on my sarcasm. Hope nobody gets offended. Cheers.

[John in Leeds]

 

John, thanks for posing the Q. It was a job needed doin', and SOMEBODY had to be fool enough to do it.

 

 

There are times when you have to step up to the line. <_>

 

Thanks for the thorough and carefully researched replies.

 

I'll just carry on as normal and NEVER let it go below the bottom of that sticky thing (Is that screwed in or out? )

[Guest ratchethack]

Good proof check, G2G. A different way 'round to the same answer (give or take). CoE seemed a more straightforward approach to me at the time, but to each his own. . .

[docc]

(Is that screwed in or out? )

My manual says , "screwed up."

[pete roper]

I think that the main reason why people suggest checking the level cold is to allow the oil to drain down and also to de-aerate. Personally I don't think it matters a toss. Check the bloody level with the bike upright and the engine turned off! As long as there is oil on the stick you know it's got some in so it shouldn't start squeaking when you're riding along! With 'Broad Sump' models it would seem pudent to keep the level towards the top of the marks on the stick.

 

Pete

[Guzzi2Go]

...As long as there is oil on the stick you know it's got some...

Well, this pretty much describes how I would understand significant (although I mentioned I will not say a word about it ). Wouldn't the proper term for what is dragging through this thread be noticeable?

[Guest ratchethack]

Well, this pretty much describes how I would understand significant (although I mentioned I will not say a word about it ). Wouldn't the proper term for what is dragging through this thread be noticeable?

OK, I'll take another run at it.

 

Hmmmmm, well, there's a considerable distinction, particularly in the context of the way the terms have been used above. That which is noticeable is not necessarily significant .

 

In the context of this thread, what was determined to be an oil level change of 4 mm over a temperature range spanning a low of 60°F (~16°C) to a high of 180°F (~82°C) is noticeable, but not significant, OR IMPORTANT, IMHO.

 

That is, it would seem that with this small amount of thermal expansion, as a practical matter, most Guzzi riders would not have to be concerned about it (or even mindful of it) for purposes of accurately gauging their oil level.

 

To recap from a perspective of making a distinction between noticeable and significant, the thermal expansion of oil is not significant or IMPORTANT to monitoring oil level because:

 

1. Most riders check and fill oil at or near ambient temps, which are generally consistent enough to negate any mis-reading of the level from one read to the next due to the effects of thermal expansion of the oil.

 

2. As noted earlier, during the course of a ride, as oil heats up from ambient temps to operating temps, under most conditions, the thermal expansion of oil isn't enough to cause an over-fill condition by inducing undue expulsion via crankcase windage through the condensor and airbox (or overflow tube).

 

3. As likewise noted earlier, under normal operating conditions, even if the oil level is read within acceptable limits "hot", after the bike cools, there is little reason for concern that the motor will starve for oil either before or after normal warm-up.

 

So you see, though a change in operating temperature of oil can have a noticeable effect on oil level under some (I b'lieve most would say unusual) circumstances, (up to ~5.7 mm on the dipstick at the most extreme temperature variations as previously shown) generally speaking, this has no practical bearing on monitoring oil level that would, for example, cause a rider to "top off" where he wouldn't otherwise perceive a need.

 

As Mr. Roper (not without considerable qualifications for saying ) has opined, "Personally, I don't think it matters a toss."

 

So I b'lieve it would be correct to say yes, the thermal expansion effect can be noticeable , but no, IMHO this is not significant .

 

Hope this helps.