Does E85 fuel increase oil consumption?

Question

I have a 2003 Opel Meriva which I run on 50% gas / 50% E85. According to my own experience and Meriva forums, this is about as much ethanol as the engine can take without tripping the engine electronics warning light. I've made at least 20,000 km on this kind of fuel, out of 200,000 km of total mileage.

Now, I have noticed that ever since I started using E85, oil consumption has increased. The car burns about 1L/2500 km now, which is not terrible, but not great either. Unfortunately, I didn't happen to note how much oil I was using before, but I believe I have to top up twice as much now as I used to do.

I wonder if the increase in oil consumption is due to E85, and is the effect permanent. I know I can just top up the oil and switch to pure gasoline for some time, but I wonder if someone already has an experience to share.

Answer 1

The E85 should not have any effect on oil consumption. E85 is just a fuel. It is my suggestion your vehicle is just getting to a stage where it is using more oil, either through burning (past the rings) or leaking out onto the ground past seals or gaskets.

Another thought may be that you were actually using the oil before you started using E85, but didn't notice the difference. It could be that before the E85, more fuel was passing by the rings, going into the oil and supplementing the oil supply (many cars do this without being noticed between oil changes). This may have offset the loss which was already happening. To check either scenario, I'd suggest you go back to using plain gasoline (petrol) and not mixing in the E85 to see what difference it makes. At least you'd know if it is being caused by the E85.

As for what you are doing, I'd suggest you rethink using E85 for several reasons:

1. Ethanol has about 33% of the fuel energy of gasoline (petrol). Your fuel consumption is probably well above what it should be. Even with the decreased cost of the E85 (at least that's the way it usually works here in the States), using it even as a blend is not going to get you the performance per litre you'd get out of plain gasoline.
2. Most cars can take E10 (10% ethanol) without issue. If they were not designed as a flex fuel vehicle, running above this issue will cause damage to your seals and fuel lines. This takes time to occur, but have no doubt, it is eating through the soft parts of your fuel system.
3. If your engine is not built to change how it runs the ethanol, you could be introducing a lean situation into the engine, which may be causing your issues. If, because of this, you experience knock, you may be causing your engine damage. At a very minimum, your engine will be pulling timing to compensate, which means decreased performance and fuel mileage.

I'm sure there might be other reasons, but these are what stands out in my mind at the present.