Theory: Gas Direct Injection Engines to Blame for Oil Consumption in Hyundai Vehicles?
Hyundais and Kias have been known to have engine problems. Just over a month ago, a class action lawsuit brought against Hyundai over oil consumption issues was dismissed by a California federal court judge, so it’s unlikely there will be any answers as to what the cause behind many owners’ strife may be—but one individual has an interesting theory.
Jalopnik shared the process that YouTuber Lab Coat Paul underwent with his own vehicle to put Hyundai’s prescribed service interval to the test. He took an oil sample from his 2017 Hyundai Tucson, equipped with a 1.6-liter turbocharged I4 engine, and sent it off to Blackstone Laboratories.
The lab conducted a series of tests on the oil for data on additives, irregularities, viscosity, contamination, and how many miles the oil’s been driven on. To Paul’s surprise, it turned out his engine was contaminated. The lab recommended a service interval of every 1,200 miles—a drastic drop from Hyundai’s recommended 5,000-mile interval.
After digging a littler deeper, Paul determined this was being caused by Hyundai’s Gas Direct Injection system, which sprays fuel at a high pressure into the combustion chamber.
GDI engines are equipped with both a low- and high-pressure fuel pump. Fuel goes in at just 60 psi, and comes out of the fuel pump at 2,000 psi—a high pressure that makes it easy for fuel to leak onto the valve cover and to contaminate engine oil.
In a fuel-injected engine, contaminated engine oil can be remedied through a positive crankcase ventilation system. For Paul’s GDI engine, though, he found no luck with cleaning the PCV valve, nor did a GDI cleaning service from the dealer, another lab test showed.
The remedy ended up being a replacement of the fuel pumps. Only when that was done did the lab results come back clean—but the ordeal highlights a stark discrepancy in Hyundai service intervals and what may actually be best for the engine. The lab’s third and final test still fell short of Hyundai’s recommendation, with a suggestion of every 3,000 miles.
