# Kia and Hyundai Water in Oil — Theta II and GDI Engine Issues in NZ

> Kia and Hyundai vehicles with Theta II and GDI engines have specific oil contamination vulnerabilities. NZ owners guide.

- Canonical URL: https://www.eek.nz/news/water-in-oil-kia-hyundai-nz
- Published: 2025-09-01
- Author: EEK Mechanical
- Publisher: EEK Mechanical, a trade name of Forman Pacific, LLC

## Theta II Engine in New Zealand

The Hyundai/Kia Theta II 2.0 and 2.4-litre GDI petrol engines — fitted to the Kia Sportage and Optima, Hyundai Tucson and Sonata — were the subject of international recalls relating to oil contamination from manufacturing debris and bearing failure. New Zealand vehicles in the affected production range (approximately 2011-2019) should be checked for service campaign completion.

## GDI Fuel Dilution

GDI (Petrol Direct Injection) engines — including many Kia and Hyundai petrol engines — are prone to fuel dilution of the oil on short trips, due to fuel washing down the cylinder walls before the piston rings can scrape it away. This produces oil that smells of petrol and has lower-than-specified viscosity. Not the same as water contamination, but a related risk.

## Water Contamination Specific Risk

Kia and Hyundai head gasket failures do occur, particularly on overheated engines. The Theta II engine's aluminium block and head are sensitive to overheating events. Any Kia or Hyundai that has been run significantly low on coolant or has had an overheating event should have its oil checked for contamination.

## EEK Service

EEK Mechanical provides oil contamination services for all Kia and Hyundai models. We carry appropriate oil specifications and flush agents for GDI and naturally aspirated applications. Call [0800 769 000](tel:0800769000).

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Source: https://www.eek.nz/news/water-in-oil-kia-hyundai-nz