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Engine RunIn - Ethanol / Alchohol based fuels

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Hey guys,

Had a client watch the engine run in webinar and asked me this question which I couldn't give him a fact based answer.

"Can we run in my engine on E85 with mineral oil?"

My preference has always been to run it in on high octane gasoline (98 RON) due to the lower chance of oil breakdown from the ethanol. I told him this mainly due to the fact I have tuned several engines that have been run in on E85 or E98 and breathed very very heavily with poor ring sealing and oil usage. I put this down to the fact that they were all run in on Ethanol as they were from multiple engine builders.

Any further insight to this one?



Personally I prefer where possible to run in a flex fuel engine on pump gas. With E85 you're generally going to be injecting 35-40% more fuel by volume and inevitably there ends up some fuel dilution of the engine oil in the sump. I can't say you should never do it but I've always done my run in on pump gas where possible.

Yep ill keep doing the same then.


As Andre suggested, where possible regular petrol/gasoline would be a better idea - but if the vehicle is already tuned for an alcohol, or alcohol containing, fuel I expect it would be much simpler to continue with that fuel but with more frequent oil changes. With a fresh build I tend to do frequent changes, anyway, with a change and filter after it's initially warmed up, with another at the end of the 'running in' period - and I'm fussy about clean builds!

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