Engine Oil

[aaronng]

hm..i heard thats no good to mix mineral and synthetic oil...my mech said that will make some sort of residue or something stuck to the engine, dont really know what they talking about but anyway i will stick to oem oil, but then he said my car is getting old and should use thicker oil, 10-30 is not enough for my 140000km engine

No, mixing it won't cause residue. Synthetic oils are also formulated to be compatible with mineral oils. Only a few synthetics are not compatible with mineral oils (and also other synthetic oils). One of the Motul 300V range is like that.

Are you having oil consumption problems when you use 10w-30 oil on your engine?