Dear Fiatforum Gurus!

I might have overfilled a bit the Stilo's 1.6 engine, when I did the oil change...

So everything went fine, I ended up putting like 0.25l oil in the new oilfilter + oiled the seals and started filling up after there was no more dripping (waited at least 20 minutes, maybe even more than that). In the 5l (Castrol 10W40 GTX Ultraclean) canister, when I finished filling up, there was still at least 1.1l, maybe 1.3l oil. Also changed air filter...

Started the car, "low oil pressure" came on for a tenth of a second, then it was running nicely. I did let it run for a minute maximum, then turned off, and checked oil level. It was a bit over than the upper mark. Maybe ~3mm over. Started using the car, everything was normal, no more low oil pressure at start-ups. After like 2 days, bit more than 50-60 kms of city driving, car started acting strange:
- Idle was uneven, but no stalling, no error message, no beeping. When I turned off AC, idle was ok once more. Another day passed, and again, when AC was on, idle was crap, and later I got a check engine light. It was both the lambdas (signals low) - those were changed 1500 km ago -, and interestingly Mixture lean... Next day I went for a 80 km B-road ride, and instantaneous consumption was horrible when AC was on and also loss of power, uneven idle, engine was running unhealthy, although no misfiring, and car smelled of petrol (mixture was rich, I guess), etc. At that time I wasn't sure about anything so I just checked (and cleared with contact spray) all the connectors that I could reach. So without AC it looked ok, was running relatively ok, idling normally, so because of that I sat off for a 1000+km trip. On the trip car worked OK-ish, but again, when I had to turn on AC everything went back to abnormal'. I tried to "clean the system" with a high speed run on the German autobahns, and for the first time, I wasn't able to reach more than ~4000ish RPM in 5th (throttle cutting off, car was shaking), but at the end of the trip it went much smoother, and was able to reach vmax.

Now, is it possible that the excess oil somehow screwed up the mixture? Should I check the inlet manifold, the sensor thingy in the top part off the airbox/inlet (MAP, if I'm correct), clean the spark plugs, and put some injector cleaner for the following full tank of petrol? Today I will check the dipstick once more and tell you how's that thing looking.

What are your advices? Thanks in advance for your help!
Best regards
wody21

If the oil is very over-full, then it could be being blown out of the crankcase vent into the inlet manifold and that oil could then be fouling the MAP sensor.

It's worth removing the inlet pipe (connecting the manifold to the throttle body) and cleaning out the manifold. Have a look at the throttle body for good measure, but be careful not to damage the air sensor wire inside it, if yours has one.

If you have a lot of oil in the manifold (like puddles of it) then clean it out. Also remove the MAP and flush it out with some solvent - WD40 or contact cleaner etc. and let it dry out. If the manifold is only "oily" but not wet with oil, then that's normal.. although it's still worth cleaning it out anyway, if you've got this far.

If your manifold is oily then some of that oil could be affecting the plugs and/or be burnt off to make soot or gum. Running some injector cleaner will help remove it.. although a cheaper option is to use 200ml (a mug full) of kerosene (aka Turpentine Substitute.. i.e. not White Spirit) c/o your local B&Q, per tank of petrol, for a few tankfuls.

Check the oil "cold" (e.g. first thing in the morning) to get a reading. If it's at 80% of the dipstick level (you may also have an Oil Level indicator at start-up, on the LED instrument panel) then that's plenty... so there's no extra prizes for getting the level precisely on MAX. Just check it every few weeks (assuming you also pay attention to the LED indicator every time you start it) and it'll be fine.


Ralf S.