If you ask the oil gurus (like Storm etc) they will tell you that the shell oil is almost as pathetic as any other oil available in the market. wether that is any PSO, shell or any local brand. The only exception is the caltex havoline which is much better but still not better.
The reason for them being pathetic is not the innate quality of the oil but because those oils are manufactured for much softer climates and easier driving conditions.
Our enviornment is much more dusty, temperature is much higher as well plus city driving harldy sees the 4th let alone the 5th gear.
If you are a mineral oil user change the oil and filter after 4000 km no matter what the oil feels like or after 4 months which ever come first. This is because you cant tell oil degradation by wether its sticky or lost its texture (and if you can either your fingers have far superior sensitivity or your oil is completely finished and has turned to water). Good mineral oil include Petromin (perhaps best bang for the buck), fuchs, liqui moli.
If you are using synthetic take up the oil changing interval to 10,000 no problem. but change the filter every 5000km as well becuase thats what keeps your oil clean and prevents damage to your engine. Good synthetic include mobil1, liqui moli etc.
Your owner manual would include the oil interval changes in the booklet, read it. If you are due get it changed, after you change it you will realise the difference.
Hope this helps.