Does wrong engine viscosity can damage the engine?

[Yoni159]

I have downtown 350 and the recommended oil is 5w40 by the book the previous owner of the scooter use a 15w50 for about 5000km can it damage the engine?
https://ibb.co/41xLD29
In the book wrote that 15w50 also possible but the recommended is 5w50 but i dont have this in my country so everyone use 5w40 fully synthetic so does 15w50 can damage?

[Stig / Major Tom]

No.
Stig

[Yoni159]

So why they wrote use 5w50 and not 15w50

[Stig / Major Tom]

So why they wrote use 5w50 and not 15w50

You ask two questions:
1) "Will 15w50 "damage" the engine. Answer is: NO, Kymco says it in an OK "alternative".
2) "Why Kymco say use 5w50?" Probably best to ask your local Kymco dealer.

But, again - previous owner did no damage with his 15w50 oil if changed at proper intervals.

Stig

[Snorvey]

Isn't the 5 weight better for winter temperatures (easier starting) and the 50 weight for normal temperature reading.

Something like that anyway. I remember it's to do with dropping a certain size of ball bearing into the oil and the time it takes to hit the bottom.

But that was 40 years ago.

[Stig / Major Tom]

Isn't the 5 weight better for winter temperatures (easier starting) and the 50 weight for normal temperature reading.

Something like that anyway. I remember it's to do with dropping a certain size of ball bearing into the oil and the time it takes to hit the bottom.

But that was 40 years ago.

Sure 5w easier starts in cooler temps - or used for 'energy saving' in newer vehicles. However Kymco owner's manual page for the scooter shows 15w is perfectly acceptable as alternate oil - thus will do no damage.

Stig