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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.

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    Its hard to figure out because your engine has 200,000km which itself is reason enough to explain that amount of oil consumption. Have you verified that you don't have a leak in one of the main engine seals? Those are sometimes hard to notice due to how dirt tends to cover up the oil. Either way, you are running a half/half mixture of E85 and gas which is not enough alcohol to ruin anything. Could it be that you started to pay more attention to the vehicle once the change to E85 was made? It could be coincidental. :) – race fever Dec 23 '15 at 15:18
  • Yep, it could easily be me paying more attention, since I was kind of expecting problems while running on non-recommended fuel mixture. – Dmitry Grigoryev Dec 23 '15 at 16:54
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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.

  • While the car does consume somewhat more fuel (about 10%), using ethanol at 0,72 euro/L instead of gas at 1,3 euro/L here in France does make a difference for my budget. I know I'm running a bit lean and slowly killing the engine while doing this, but given the market price of my car I'm not bothered. Anyway, I will try switching back to pure gasoline and report once I have results (it may take a few months though). – Dmitry Grigoryev Dec 23 '15 at 17:05
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    I would not recommend to use the market price of the car to judge whether you should slowly kill the car. Even if a car has low market price, if it is perfectly functional then it is a very valuable tool to YOU, the owner. A low market price essentially means you shouldn't sell the car; it doesn't mean you should destroy the car. Consider this: can you purchase an equivalent car with no additional defects and with a fully known history? I doubt it, unless you purchase a new car. Every second hand car has an element of uncertainty. – juhist Dec 24 '15 at 17:18
  • @juhist - Well said. – Pᴀᴜʟsᴛᴇʀ2 Dec 24 '15 at 19:56
  • Wouldn't the increased octane of the E85 reduce knock? – 3dalliance Jan 24 at 19:44
  • @3dalliance - While that is correct, it does not relate to the OPs question, therefore not mentioned. – Pᴀᴜʟsᴛᴇʀ2 Jan 24 at 21:57

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