put unleaded gas on accident

[gtecd20]

so my dad borrowed my car and decided to be nice and fill up my tank of gas, he accidently put reg unleaded instead of Pre unleaded.

will this do anything to my engine or do i just need to grab an octane booster and will be ok?

thanks for the help

[poeticfinesse21]

Assuming you still have the K20A3, then 87 octane is what you're supposed to use anyway. 91 or 93 octane doesn't do anything for our motors, it was designed to run off of 87 octane gas.

[EUB44]

^^ x2.

[dble0]

I stopped putting 91 octane in about 8 months ago. I don't really see the difference in either direction. All that money wasted.

[gtecd20]

I thought if UR running a jrsc r it has to be pre unleaded

[USAF EP3]

Drain the tank as much as possible and fill with 93. Since you got a JRSC it makes boost all the time. I wouldn't risk it, even though you MIGHT be okay pussy-footin' it around you still run a risk.

[gtecd20]

I went ahead and threw a Lucas octane booster I'm sure that should help it

[USAF EP3]

I'd put like 10 bottles LOL!

[playap07]

When i first got my EP I used to fill up with the unleaded gas. My car used to get horrible mileage on the highway when i was running this (my opinion). Then i was reading the owners manual and it said something about premium so from then i used premium. Unleaded didnt do anything bad to me besides bad gas mileage but thats just my opinion from 6 years ago. You should be good as long as your not turboed or running high compression.

[gtecd20]

so far car is running little bogged but im already at half a tank, seems to get worse gas milage with reg

[USAF EP3]

so far car is running little bogged but im already at half a tank, seems to get worse gas milage with reg

Top off with 93 (or 91 whatever is premium) again. It'll make similar to an 89-90 mix.

[poeticfinesse21]

I've been keeping track of my MPG since I bought my EP3 two years ago and the octane makes no difference. What affects your MPG the most is your driving style. The only thing premium does is keep my P0420 cel off

[danito321]

From what I know, the higher octane is needed for turboed or charged engines and high compression engines. Otherwise it's just overkill in a a3. I don't notice a difference even though I wanted to believe so. However my friend had his wife put low octane gas in his gti and he got engine knock I guess and messed something up.

[.colin]

I've read that the stock a3 can benefit from 91 or 93 octane gas. The ecu will advance timing until it senses knock.

[allezjohn]

I did a little experiment with last two fillups with premium gas and noticed my engine felt a little more power and MPG went up. Now, my engine is stock, no supercharger. Only an Ingen sri. I do live at ~7300 feet elevation. Was getting around 27mpg on regular, jumped up to 28.1 on Premium. I normally get ~34mpg once we are on Summer gas. Same driving routes, and if anything my style was a little more 'foot heavy' with the premium tanks. Also calculated it out to Cost per Mile of $0.14 per mile with Regular and $0.15 with Premium. Maybe with Kpro tuning for the altitude, etc, I could improve that number. For 1 more penny per mile, my car was a lot more fun to drive... I'll take it.