Last time I changed my 'oren' engine oil was Jan 2011. Because of I am using petronas semi-synthetic 800 (15w-50), I am trying to stretch my mileage to 10,000KM. But until August 2011, my mileage hasn't reach 10 K yet. So I planned to downgrade my engine oil back to mineral.

My brother in law did that for me. He changed to Shell Helix HX5. But I am not sure whether it was 15W-40 or 10W-30. Now I am back to 5000K change interval. And I did some comparison between Shell Helix HX5 and PETRONAS Mach 5 SM 15W-40. I found that Petronas lubricant is much more better than Shell Helix HX5. Its due to the ACEA standard where shell is A2/B2 and petronas is A3/B3. And here is the summary.

Petronas Mach 5 Shell Helix HX5
ACEA A3/B3 A2/B2

So I planned to shift to Petronas Mach 5 for the next oil change which will be 54,500KM.