Gah - Oil has gas smell (still)

Hey Everybody -- been away awhile, but just did my third oil change at 6,500 mi interval and old oil smelled like gas again for the third time. After about 100 miles of daily 25 minute commute (both ways) and a 45 minute trip (each way) new oil on dipstick smells like gas. I don't know if it's strong or slight -- I can just notice it. I cleaned my MAF sensor around the last time I changed my oil. Not noticing anything untoward with performance maybe a slight decrease in MPG -- instead of 20-21 hwy I'm getting around 19-20 and 17-18 city instead of 19.3-19.7. I've created a dashboard on my OBDLink MX+ with Short FT B1S1/B2S1 -- Long FT B1S1/B2S1 -- Air-Fuel Ratio -- hoping this gives me a little insight, but only marginally sure I can interpret the data. Also thinking about doing an injector cleaner gas treatment.

Any thoughts, advice or tips? I'm worried that this running rich is harming my engine and I'm coming up on 100k (99,200 now) -- what's the best course of action? (stop worrying so much maybe?)

 

This probably won't help you at all, but I asked Mr. Google about your question and this is the answer I got:


AI Overview

If your engine oil smells like gas, it's important to address the issue as soon as possible to prevent damage to your vehicle's engine. Some possible causes include:

• Fuel leakage: A faulty fuel injector, fuel pressure regulator, or damaged fuel line can allow gasoline to enter the oil.
• Incomplete combustion: When the fuel-air mixture isn't ignited properly in the combustion chamber, unburned fuel can end up in the oil.
• Worn piston rings: If the piston rings are worn, oil can get into the cylinders.
• Oil cap leak: A gasket on the oil cap can cause fumes to leak from the engine.
• Spark plugs: If the spark plugs aren't tightened properly, they can leak fumes into the combustion chamber.

Some things you can try to fix the issue include:

• Closing the fuel shut-off valve when the engine isn't in use
• Cleaning the carburetor
• Checking the fuel pump

 

First thing you need to do is confirm you have a real problem. Would an oil sample analysis or two identify fuel if it's there? I'm not familiar. But if fuel is identified, it becomes a hands-off (for you) warranty issue.

 

Thanks for the feedback -- UPDATE -- I ran the dashboard during a 30 minute hwy drive -- looks like the Long FT (fuel trim) sensors are reading about 6.3 - 7.8% which is above the 5% cutoff that indicates running a rich fuel mix -- don't know -- maybe I should do a fuel injector cleaner gas treatment -- anybody have any thoughts on those? And yeah, maybe I should do a Blackstone analysis.

 

Have your performed a compression and leak down test before going down this path on what you think is taking place?

Get some good base information on the actual state of play to say, on your engine, Use this important information to aid in troubleshooting the perceived issue. Take a scientific approach and let data drive the decisions of your next move.

 

I'd like to, but that may be a bit over my skill level -- don't really know how to do that

 

I would take the "Artificial Intelligence" diagnosis with a HUGE grain of salt, the AI took every possible cause and cure and grouped them all together even though some of them only apply to certain generations of vehicles/mechanical technologies and not together on more modern vehicles.

 

Hey, if you can't trust a faceless robot who CAN you trust?

P.S. This is how Terminator started. The machines rose up after being programmed to learn & think for themselves.

 

Would running 87 vs premium gas have anything to do with this?

 

Simple suggestion… The Car care nut has a video about a 4 runner with a lose hose on the intake causing excess gasoline to enter the combustion chamber. YouTube Title “This 4Runner almost lost an engine”. Try watching the video where he explains the lose hose and what it causes. This may help.

 

funny I just watched that, think the hose was disconnected -- caused a massive hydrolock with a piston fully filled with gas

 

Also -- just did a hwy drive -- 25 minutes -- when I got home, oil still had that gas smell -- so I guess that means it's not burning off, or maybe the injectors leaking? I don't know

 

Maybe the regulator the hose connects to is starting to go out or the hose may be leaking?

 

You could stop it after driving through one of your cycles, remove all the plugs and inspect the cylinders after a set amount of time to see if you have an injector straight up leaking into the cylinder(s)

 

If the engine is running fine, and the MPGs are largely normal, and your oil level doesn’t increase between oil change intervals, I wouldn’t go looking to fix anything. Some smell of gas in oil is inevitble, so you being able to “just” smell gas makes it sound pretty normal.

I’m disappointed it didn’t include a suggestion to inspect fuel rail fluid pressure differentials. We all know nature hates a vacuum, so If there’s a big differential, it will equalize in whatever way it can. This means, the fuel pressure will move towards the oil pressure chamber to remove that differential.

(nobody correct my word salad, I’m just making sh*t up lol)

 

Wait until you have 1-2K and drain and send off for analysis to Black Labs. Tell them you are concerned about fuel in the oil.

 

Man — I’ve taken a couple of hwy drives after work (25 min through crosstown traffic) and oil still smells like gas afterwards— now I’m running some Techron High Mileage fuel system cleaner through it to see if that helps before I take it to a mechanic

 

Here’s to hoping that a mechanic doesn’t charge you lots of money only to tell you not to worry about it, or replace unnecessary parts, or to send off your oil for analysis.

 

I would think with today’s engine monitoring, that if the fuel mixture was that far off, you’d be getting fault codes.

 

For what it's worth, the oil in my 2018 smells like gas all the time. Has since new. Problem free vehicle so far.

 

according to this

https://trade.mechanic.com.au/news/understanding-short-term-and-long-term-fuel-trims1

if you go over +-10% then you should be worried..

I think you are ok..

what oil are you using?
also, try to change your gas station....

I have the same thing and my LT fuel trims were normal..
it is due to short trips and the nature of the combusion engine....

 

I think you are way over thinking/worrying. Is the engine/dash/service light on? No, then just drive the thing dude. Its fine.

 

I use an OBDLink MX+ and the Long FT 1 & 2 usually stay between 0 - 5.5%, and 6 - 7.8% (pegged out so possibly more?) under acceleration. As for oil, I only use Toyota OW-20

 

Wifes 2005 Corolla has had this since new. 215,000 miles. I changed every 5K. Don't over think it.

 

When you say pegged out, do you mean that it’s pegged out on the app you’re using? I would think it just looks pegged due to range chosen for display on the app, but that the app itself would still give you the actual raw values.

I forgot to mention this before, but I had a 2011 Optima I bought new. The engine was gasoline direct injection. Now THAT car had some gassy smelling oil. The oil itself turned dark very quickly, by the time it had 5000 miles on the oil, it was tar black with hints gray swirls. Disgusting. It ran fine for yhe 95k miles I owned it, but it did not inspire confidence. I didn’t even bother trying to figure out that gas smell. Traded it before it has 100k miles. I figured it was a inherent problem with their GDI engines, and maybe the reason those engines were failing left and right.

What does your oil look like on the dipstick? Has it started to look different recently?

Oil color by itself doesn’t mean anything, but unexpected changes to what it normally looks like can be cause for concern. If nothing has changed, I wouldn’t worry about it. In fact, worrying about it could be worse for your engine, if it means you’re having people tear into it without a solid justification. If the *only* symptom is being able to barely detect a hint of gasoline smell in the oil, I personally would not treat that as a justification to look at anything more closely.

If you feel a need to do something, maybe simply cleaning the throttle body, cleaning the mass air flow sensor, and replacing the air filter will result in changes to fuel trim. I don’t know how to interpret fuel trim, but at least this is common maintanance that keeps cars running well (assuming the cleaning is done correctly).

 

Are you making oil between oil changes? If not I personally wouldn't really sweat it too much.

Or send it in for an oil analysis to see if it really is fuel and how much getting in.

 

I had this concern with my Tacoma and sent a sample to blackstone and it came back A-OK and they suggested even stretching out the oil changes another 2,500 miles based on the condition of the oil. It’s a cheap peace of mind to just send the sample as others have suggested. I haven’t thought about it again since to be honest.