It won't do any harm but Helix ECT C3 is not the version I would choose for a C180K because it's based on ACEA C3 which makes it a mid saps oil intended for diesels with particulate filters. The original spec for a C180K was 229.3 or 229.5 which are based on ACEA A3/B4 making it a stouter oil with higher HTHS. I use the standard Helix Ultra in a 5W40.