What oil to use

[2001SE]

I have a 2001 Acura Ingra, currently using castrol GTX 5w30. I was thinking of maybe switching to synthetics, but not really sure what brand or grade to use. I live in Canada so winter can get really cold, that would be the main reason of switching to synthetics. What do you guys think?
Thanks

 

[02zx9r]

Pennzoil Platinum 5W30, AMSOIL Signature Series 0w30 etc...

Mobil 1 is great for very cold starts

 

[2001SE]

Is it worth it to switch to synthetics? I have 140 000KM on my engine could it do any harm to it?

 

[ZZman]

Always worth it if you love your car and want to keep it. Harm it, NO

With the miles you could try Valvoline Maxlife Full Synthetic or Mobil 1 High Mileage.