gasoline odor in oil

[CamasM3e93]

I did a day-off oil change at 5k miles yesterday, my first on the car having bought it in July with 45k miles, now just over 50k. Over the course of this oil change interval, I've (and in order):

--changed plugs (NGK Iridium, but I bought them on Amazon)
--installed aFe cold air intake & uploaded BPM Stage I performance software + --DCT software in October
--installed TMS power pulley in November (along with coolant flush, water pump, thermostat)
--installed AA test pipes / primary cat delete in December

The car smells like it runs rich at start up since the software change, which included elimination of the cold start routine. BPM reports this is not common occurrence for their software.

Oil change was Castrol 10w60 supercar in July and December.

The car runs strong. No rough idle, no misfires. I've had maybe two occasions where the car lurched at neighborhood speeds when it was cold, like I had pressed harder on the throttle than I intended but it's not followed by anything of note.

I have zero CEL, have had none in the interval. I did get a warning in September that I'd overfilled the crankcase. I was in the middle of a trip and drove it until it burned off to level.

I do drive it on short trips at times where it doesn't come up to full heat. I get no white smoke, there's no oil in the coolant.

It was burning appropriate amounts of oil through September, adding around a liter every 1000-1500 miles but somehow the oil burning stopped sometime after that - or seemed to as the level stopped dropping until just recently it came down 1/2 L before the oil change.

So, dear M3 enthusiasts - why does my waste oil smell like gasoline? (Oil analysis to be sent)

--Misfiring / non firing counterfeit spark plug? - not idling roughly, no CEL
--leaking fuel injector after shutting car off? - doesn't start rough, doesn't blow foul smoke after starting
--Fuel injector wide open? car just drove 30+ miles at highway speed and through mixed city driving after discovery with zero issues, no CEL.

Short trips not getting oil up to temperature? this is my guess but the oil seems to smell too much of gas for that. Anyone run into this on their M3 with frequent short trips? I'm trying to decide whether I take it to a garage for a lengthy diagnostic or just send in the oil analysis overnight and wait.

[Pig Farmer]

This is pretty normal from my experience. My drive to work is only a few miles, so I have hundreds of short trips between oil changes. Even though the smell of gasoline seems stronger than previous cars I’ve owned, my Blackstone reports Come back completely normal. If you’re not experiencing any codes, I wouldn’t worry and just wait for the oil analysis results.

[CamasM3e93]

Thanks, that's the experience I was looking for. I'm going to go ahead and change my pre-cat oxygen sensors as well - I'm seeing some experience of running rich due to wayward old sensors. I couldn't help but shake my head at myself doing a cat delete and putting 8 year old sensors back in place at the time. But I can see that the two situations may not be related.

[DRLane]

You removed the 400 cell primary cat, welcome to the test pipe smells. Wait until you go full catless

[akkando]

Probably unrelated but isn't a stage 2 tune recommended if primary cats are removed?

[RedScytheM3]

It's probably normal for the oil to smell of gas. Mine did the last time I changed it. Pretty sure small amounts of gas gets introduced into the oil inside the cylinder and builds over time.

[CamasM3e93]

Originally Posted by akkando

Probably unrelated but isn't a stage 2 tune recommended if primary cats are removed?

Two months after the Stage I tune I decided to do the cat delete. Yes, I will get additional performance gains when I add the stage II tune, in addition to the CEL fix. For the moment, my 90-degree elbow spacers on the downstream oxygen sensors are preventing the CEL from tripping.

[CamasM3e93]

Originally Posted by DRLane

You removed the 400 cell primary cat, welcome to the test pipe smells. Wait until you go full catless

Nah, I ran on the Stage I tune (smelling rich) for two months before the cat delete.

[DRLane]

Data log and share with BPM. I think you said you were going to replace the precat O2s, I'd start there?

[CamasM3e93]

The end of the story - I did replace both pre-cat oxygen sensors. Rich/gas smell with cold ignition now gone. All that remains is the smell from removing two-thirds of the CAT capacity, as it should be. Also, oil analysis came back from Blackstone showing no measurable fuel level in the oil.