I have a van here with almost 700000kms on it. On the original engine running basic conventional oil and filters every 5000kms. I don't think it'd still run as well if at all if I changed the oil every 20000kms. Or maybe it would?
For the Mirages, I use 0w20 synthetic, city cars are changed at 6000kms, highway car 12000kms. And a few randoms go around 8-10000kms. Haven't had one fail yet. But now I said that ones gonna crater this week.
Mirage videos:
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View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)