5w30 for the rest of its life?

[abimanyu]

My rolla is a 2003 with about 27000 km in it. I was thinking of using 5w30 for the rest of its life. My question is, should I change viscostiy as the car gets older? Should I change to 10w30 when it reaches 30000km?

I once used IGOL(from France under TOTAELFFINA I suppose) Symbol Ceramic 5w40 and I noticed that the engine runs quieter and smoother and more responsive than using IGOL Compact 5w30. I don't think you can find these oils in the U.S but it seems that the 5w40 makes my engine quieter and more responsive than the 5w30. Since the 5w40 is not recommended in the manual, can I use 5w40 full synthetic?

Thanks

[shadowsun]

As I understand it, using a heavier oil is usually a solution for when the engine is knocking or drinking oil. (A temporary solution.)

As for how you'd get better performance off a heavier oil.. I'd love to know how this is possible. It seems to me that a higher viscosity liquid would require more effort to move... I suppose if it makes something heavy and important move more easily, it might make sense, but I don't know.

[abimanyu]

I can't explain it either, but it seems that when I used the 5w40 from IGOL Symbol Ceramic Line(you can check their site) the engine sounded smoother, less valve noise and the pick up is peppier, I don't know, could it be the formula in the IGOL Symbol Ceramic 5w40 is different than their IGOL Process Compact 5w30? The oil line is different, the IGOL Symbol Ceramic is above the IGOL Process Compact line(both are full synthetics).

Postscript to that, I noticed also that the IGOL Symbol Ceramic 5w40 doesn't get darker as fast as the 5w30, come to think of it, it stays clearer much much longer. Could it be that there's less detergency in the 5w40 than the 5w30, similar to that of a racing oil that contains less detergency than street oil.

My question is, is it ok to use full synthetic 5w40 eventhough the manaul only recommends 5w30 or 10w30?

I want to use the 5w40, will this be ok?

[shadowsun]

About that, I honestly don't know :/ I have run into people who swear it's bad to use any oil but what's recommended, and people who say it really doesn't matter. I tend not to care too much, but I also have never owned a car newer then a decade old...