Questions for the FFV owners...

Are you guys running flex fuel? If so are there any pros or cons? I have a 2018 CM FFV but have yet to run any E85. Ive only ever ran regular gas. Is there any downsides to switching back and forth? Any feedback is aprreciated.

 

I also have a 2018 FFV Tundra and will probably not run E85 in it only because it is not readily available in my area, have to drive 30 mins to get some plus there is no economic benefit at the moment with gas at $2.20 a gallon in Texas.

I can give you some feedback on my 2013 Tahoe with the 5.3l FFV motor. I run a full tank of E85 through it before each oil change. I have found the E85 works really well to de-carbon and maintain the piston and oil rings that started to foul on the AFM cylinders (cylinders that deactivate so truck runs in v4 mode). I was having major oil consumption issues (1qt every 1k miles) with my 5.3l at 30k miles and learned the AFM causes issues with oil ring fouling and carbon buildup on the pistons. Other owners had great success by eliminating the v4 mode from activating and using E85 to help de-carbon the cylinders. GM's solution, to those under warranty, is to pour top end cleaner down the spark plug holes and if that didn't work replace the bad pistons, once outside the 36k warranty you are out of luck . I am happy to say I no longer burn any oil between changes and truck has run much better the last 3 years by running some E85 before the oil change (I also tried BG engine cleaner, techron additives, Mopar Combustion Chamber Cleaner all which may have helped but the E85, V4 elimination and shorter OCI did the trick for me). One other notable benefit I have found is the truck runs so much smoother and feels more powerful with E85, but I lose 3 mpg on it too. I have read about the wear characteristics of running high percentage ethanol exclusively from some paper that was compiled in Brazil to compare internal component wear. The findings did show E85 can lead to slightly higher wear over a long period of time to components exposed to high % ethanol fuels but I can't recall the percentage wear difference. I imagine that is why Toyota requires the oil to be changed every 5k miles if you run E85.

 

Don't run it. Short and simple. Search the forum.

Only benefit to E85 is if you are boosted and tuning for higher octane.

 

E15 E20 E30 will run just like regular with E50 and up you will see some mileage loss per gallon

 

There are a bunch of threads on this topic, The short answer is if you have a choice don't run it. Heck even the owners manual says to change the oil and filter every 2500 miles if you do, 5000 if you don't. The regular gas engine is 10,000 miles between oil changes. That should be enough information not to use it.

-Jason

 

Not to question a engineer that definitely has more book smarts than me but I wonder why they cut the mileage so short for oil changes.

The work truck I have is a Chevy and we're supposed to be using E85 for fuel and we have been told to do our oil changes in the 7500 mile range. This with GM knowing that these are hard use and can have long idle times or not be turned off for 14hrs straight. Those of us with access to E85 have been running it for years with no engine issues. Can't say the same for the rest of the vehicle but no engine issues to date.

 

BIGUGLY, thats a good question, that I don't have a answer for. But if you do have an issue engine related and you cant produce proof that you followed the scheduled maintenance schedule, they can deny the warranty claim.

-Jason

 

E85 has been shown in a variety of vehicles to cause oil contamination greater than fuel with 10% or less ethanol. This is across the board through all manufacturers. You will find this in forums and on Bob is the Oil Guy. Lots of good info with lots if oil analysis and lab results.

That is the reason that DILIGENT manufacturers cover their ass and reccomend lower mile oil change intervals.

But again simply, just don't run it unless you're looking for a cheap alternative to higher octane race fuel.

 

Good to know