Engine oil grade 10W-30 or 0W-20? - Suzuki Alto K10

[the_wayward_one]

First of all I want to disclose that I know very little about cars. I bought a used Alto k10 exactly a year ago (80,000km), and I've done a few engine oil changes so far (drove 18,000km so far). Primarily with Castrol 10W-30 (as per the previous owner's records and confirmed okay by the garage, and one with Luk Oil 10w (either 30 or 40) that was recommended by the garage as they didn't have Castrol. On an alternate note I noticed a significant drop in performance after using Luk Oil, the car does not accelerate as well. I came across the Alto K10 manual document online, and the recommended engine oil grade is 0W-20. Is this is a problem? Should I switch to this instead?

[kush]

what was the performance drop power or economy

There can not be a significant drop due to difference in viscosity.

10W-30 should be ok for the ALTO, 0W-20 will give you little more economy and better emissions.

However if the car has run on 10W-30 for the last 80K km it may have got run in for the thicker oil and changing now could increase oil consumption.

40 grade would be too thick for your car and i would not recommend it at your current mileage. It may be ok for a older high mileage car when the oil burning stats to kick in.

My view is your issue is not oil related   

[the_wayward_one]

Thanks for the response and input! I have not noticed a difference in economy, but the car is slower to accelerate. It's so obvious even my wife, who knows even less about cars than me lol, noticed. I'll probably take it into a garage if it's not oil related and get it checked out!