Preventing and Addressing Oil-Burning Problems in a GDI Engine
A few readers have told me that they'd like a page specifically addressing why cars with GDI engines tend to burn oil; as well as how to prevent, reduce, or stop oil-burning problems in GDI engines. This page attempts to address those questions.
Before we go on, however, I suggest that you read the pages about choosing a motor oil for a GDI engine, and the importance of keeping GDI engine intake systems clean, if you haven't already. This page builds upon the information presented in those two pages.
Where this page differs is that it specifically addresses the topic of oil-consumption in GDI engines, rather than the more general topic of carbon buildup. This page shows how the carbon problems contribute to the oil-burning problems.
Why do GDI Engines Burn Oil?
The short answer is that when they're clean, GDI engines don't burn any more oil than any other engines do. The problems begin when carbon deposits start accumulating on the intake valves. In carbureted and port fuel-injection engines, the fuel wash from the gasoline mist in the induction system helps keep the valves clean. In GDI engines, the gasoline is squirted directly into the cylinder, so that doesn't happen.
Carbon deposits on the valves, in and of themselves, contribute more to performance-loss issues than oil-burning problems. But when those deposits slough or flake off, they can become lodged in the piston ring area, which does directly increase oil-burning.
That's also why addressing oil-burning problems in GDI engines requires a three-prong approach:
- Choose an oil specially formulated for GDI engines (my current favorite being Castrol Edge Advanced Full-Synthetic GDI formula) to reduce crankcase vapors that lead to carbon problem on the valves. If your car is older and is also leaking (rather than just burning) oil, consider a high-mileage oil formulated for GDI engines like Castrol Edge Advanced High-Mileage.
- Regularly clean the induction system with a good intake cleaner like CRC, Berryman, Seafoam, or Liqui Moly, following the label instructions, before every oil change.
- Treat the gasoline with a good fuel cleaner that contains enough PEA to remove carbon from around the rings, like Techron Complete Fuel System Cleaner, around the same time as every oil change and induction-system cleaning. The intake cleaner will also help clean around the rings, but only during its application. The Techron will keep working on the rings until the next time you fill the gas tank.
If at all possible, you should also use TOP TIER gasoline whenever possible. A study by the Automobile Association of America in 2016 revealed that non-TOP TIER gasoline produced as much as 19 times the deposits that TOP TIER gasoline did.
Cleaning and Maintaining the PCV Valve
Because the PCV (positive crankcase ventilation) system is one of the major sources of carbon in the intake system, and eventually the combustion chamber, checking the PCV valve often and cleaning or replacing it as necessary will also go a long way toward reducing carbon deposits and preventing oil consumption.
Fixed-orifice PCV valves use a hole whose diameter was engineered to help maintain equilibrium between the crankcase and intake manifold pressures, while dampening the pulses and minimizing oil entry into the induction system. Spring-and-plunger PCV valves are check valves that open when the crankcase pressure exceeds the force of the spring holding the check valve closed. When shaken along their length, you should be able to hear and feel the plunger moving. Either type of valve needs to be inspected regularly, and cleaned or replaced if necessary.
PCV valves are cleaned using carburetor and throttle body cleaner. If the PCV valve is a fixed-orifice type, just spray the fluid into it until it comes out the other side clear. If it's a spring-and-plunger (check valve) type, use something like the long arm of a small Allen wrench to depress the plunger while spraying the fluid into the valve from the end that attaches to the crankcase. Shake it a bit, and then spray the fluid into the other end. Repeat until the fluid comes out clear.
If the plunger is stuck, doesn't move smoothly, is severely clogged, or the spring is broken, then replace the PCV valve.
Preventing Oil-Burning Problems in GDI Engines
If you follow the above regimen religiously from the moment you buy your new, GDI-engine vehicle, chances are your car's engine won't develop an oil-burning problem. Choosing the right oil (and gasoline) minimizes the deposits, cleaning the intake system regularly removes what carbon does get on the valves, and treating the gasoline prevents the carbon that's removed from building up around the rings (as well as removing deposits from normal combustion and other causes).
If your driving consists of frequent short trips, you also should consider reducing the oil-change interval to about half the time and mileage that the manufacturer recommends (or alternatively, follow their "severe duty" recommendation for oil change intervals). Chemical breakdown and oxidation of oil components (as opposed to physical breakdown such as polymer shear), including detergent breakdown, occurs even if a car is never driven. Water contamination due to temperature changes is also a big problem with cars that are infrequently used.
Treating Oil-Burning Problems in GDI Engines
If your GDI-engine car or truck is already burning oil, then I suggest you follow the following steps to help stop, or at least reduce, the GDI engine's oil consumption.
- A few days before an oil change, add a can of Techron to the tank and fill it up. This is important because the next step will be loosening deposits from the valves, and you don't want them getting stuck between the pistons and cylinders or around the piston rings.
- Immediately before the oil change, clean the induction system using a good intake cleaner like CRC, Berryman, Seafoam, or Liqui Moly, following the label instructions. If your engine is burning more than a quart of oil per thousand miles (about a liter per 1,600 kilometers), do this step twice, driving between 25 and 50 miles (about 40 to 80 kilometers) between the two treatments.
- Change the engine oil and filter using an oil specially formulated for GDI engines like Castrol Edge Advanced, Total Quartz INEO, or Valvoline Modern Engine Oil. The Castrol is my personal favorite. Look for the bottle that says it's formulated for GDI Turbo engines right on the label.
- Add another can of Techron to the gas the next time you fill up.
- Repeat the whole process starting with Step 1 in about 1,000 miles (about 1,600 kilometers) or so.
You should also check the PCV valve, and clean or replace it if necessary, as described above. This is a regular maintenance item that should be performed regardless of whether your vehicle's engine has an oil-consumption problem.
The above process is pretty much what I did when my own GDI-engine car started burning oil. Now it no longer burns any. I did an oil change a few days before I wrote this page, and there was zero detectable oil loss since the previous oil change.
Now the Bad News
The bad news is that the procedure outlined on this page isn't a one-time fix. It's something you'll have to keep doing for as long as you own your GDI-engine car. Maybe you won't have to do it every time you change your oil like I like to do; but if you stop doing it altogether, eventually your vehicle's engine will burn oil again.
If I had to choose one of the above steps as being the most-important one, I'd say using an oil formulated for GDI engines would be that one step. That's where most of the carbon on the valves comes from in the first place, so minimizing it at the source is critical. But repeating the above process at least every other oil change would be even better.