Engine Temperature - Agility 125

[scooterfan]

For what it's worth - some time ago I decided to get an oil temperature reading with my bimetallic thermometer after a ride of about 8 km  on my Agility. The ambient temperature during the ride was about 24 deg. Celsius , and I just put the thermometer's stem into the oil filler hole immediately after the engine has been switched off.

The temperature reading was 75 degrees Celcius after about 3 minutes - but knowing how this thermometer normally works, I realized that the real temperature was suppose to be closer to 80 deg Celsius. The reason being - previous tests proved that this thermometer is very accurate, but only if the fluid level is as close as possible to the indicator back plate. During this test the oil level was slightly lower than the top of the oil filler hole - so I knew the temperature reading would not be 100% accurate.

This test actually proved to me that Mineral Oils should not be used on these engines. According to some reading elsewhere I once noticed that Mineral oils start degrading at temperatures higher than 80 deg. Celsius. Synthetic oils only start degrading at much higher temperatures.
As mentioned above - on the day I got this temperature reading the abient temperature was not too high. I can just imagine - on a very hot day the oil temperature could easily be higher than 80 degree Celcius...

Photos of my thermometer, as well as the temperature reading during the test.

 

[monkeybongos]

Good info.  Any reason not to use a synthetic car oil?

[scooterfan]

Good info.  Any reason not to use a synthetic car oil?

These scooters do not have “wet” clutches so there should be no reason why synthetic car oils should not be used. I use a synthetic car oil anyway. More than 25 000km on the clock at the moment and the engine still runs like new.

[Iahawk]

I think it was on a vespa forum where everyone was going on about how you should use a motorcycle oil in an air cooled scooter with cvt tranny. That's ridiculous. I think people forget that our motors are basically lawn mower engines!

No wet clutch involved so no reason to use a motorcycle oil. I do think synthetic is a good idea (although my current fill is regular old Pennzoil yellow bottle 10W-40).

Back to your temperature reading..I would have thought it would have been even hotter? I was under the impression that oil would exceed 100 degrees C (212 F) in order to boil off any existing water that may have condensed in the oil.

[scooterfan]

I think it was on a vespa forum where everyone was going on about how you should use a motorcycle oil in an air cooled scooter with cvt tranny. That's ridiculous. I think people forget that our motors are basically lawn mower engines!

No wet clutch involved so no reason to use a motorcycle oil. I do think synthetic is a good idea (although my current fill is regular old Pennzoil yellow bottle 10W-40).

Back to your temperature reading..I would have thought it would have been even hotter? I was under the impression that oil would exceed 100 degrees C (212 F) in order to boil off any existing water that may have condensed in the oil.

You are correct - as mentioned in the last paragraph of my initial post,  the reading was taken when the ambient temperature was only about 24 deg Celsius. That’s quite lower than normal temperatures during our summers. My point was that oil temperatures get that high during fairly low ambient temperatures - it should get quite higher during mid- summers.

I also forgot to mention. That reading was taken after a fairly slow ride in town. If the temperature was taken after higher speed outside town I think the reading would be much higher - even when the ambient temperature was about 24 deg Celsius.

[Stig / Major Tom]

A temp reading taken 3 mins after a forced-air cooled engine has been shut off and left to 'cook' - will likely be higher than the temp of a running forced-air cooled engine.

Obviously mineral oils didn't routinely kill air cooled motorcycles, cars or scooters over the decades - but I won't argue that I'd feel better with a nice blended oil in there these days (although....yrs ago I stopped using Mobil One in my Beetle when it sprung leaks after the first try)
Stig