Changed my oil changed my idol ?

[boxster03]

I did my usual 6,000 mile twice a year oil change and my high idol is now spot on 900 rpm why

the oil was very dirty from a couple of long trips and use of a lot of Chevron Techtron and there was a little bit of metal stuck on the oil plug but why the change in idol speed ? (from 1100 to 900)

No other adjustments except the oil change. happy but confused

[boxster03]

American Idol

Not a new engine original with 69,000 miles. There were 2 large pieces of metal in the oil no shavings but 2 chuncks. Oil was black from the techtron. Mystery as to why the idol change

[72targa]

The oil would normally be dark because of the detergent/dispersant additive package in it that is keeping all the sludge in solution rather than allowing it to coat the inards of your engine. In fact, it may be cleaning out leftover sludge. You could possibly be using too much Techron which can get from the combustion chamber to the engine oil past the piston rings.

Don't use too much Techron. It is a great product but you can actually excessively thin out your oil with it. Follow the directions. I believe you are not to use more than two bottles (proportional to your gas tank volume) between each oil change.

[boxster03]

thanks.

I used a bottle in every fill from austin to boulder and back so that was a lot of techron

[Fritz A. Ficke]

Becouse the engine also sucks air out of the crankcase to vent it, your oil fumes have an effect on your fuel/air ratio, most noticed at idle. Engines cold, do not burn all the fuel and some of it goes in the oil ( one of the reason to change oil). Old gas soaked oil will make engines run richer and sometimes even enough to change the idle.
I have changed oil on cars and that was what it needed to pass emmission test. Fritz

[boxster03]

Thanks Fritz for an excellent explanation. I bet that was what was happening.