Blue smoke in start up

I have a 2008 mustang gt with 230,000 miles on it.(Runs great) Recently it started to push smoke out on startup. Didn't think anything of it. Now 3 out of 5 times I start it cold, it pushes blue smoke.

I know it's probably just the value seals, but do you think I can bump up the oil to 5w-30 high mileage?

And would it hurt or help?
Thanks

@230K, what's the maint history on your motor? Has anything been services/rebuilt/upgraded (stock vs. performance)? How long have you owned? The list can go on...if you want help.

It's been my commuter car for the past 5+ years. Only "performance" mods are axle backs and driver-side catch can. Everything else stock. I recently stopped driving it every day and that's when I noticed the smoke.

You can keep driving it. High mileage oil won't hurt but probably won't help either. If you are still using 5w20, I would definitely go to 5w30, that will help a little. Burning a little oil at 230k miles is not a big deal.

@230K it is hard to say. Have you checked the catch can to see if there is more oil than normal in it?

Have to say you've gotten your $$$ worth from the motor. Start w/ the oil weight change, listen f/ strange engine noises & keep driving. What's the worse - rebuild, or swap...right?

Use 100% synthetic ..and not that semi- synthetic junk. I would suggest 5W-30.
When we switched from semi synthetic to 100% synthetic, my driver's side catch can went from full every 6 months...down to virtually nothing. At least 10 of us noticed the same thing.

Is this car tuned? Sometimes that causes overly rich startup resulting in blue smoke. Probably not it based on the milage.

But, I have a 2v pushing 175k, zero smoke. Would use no oil if Id fix the small leak. lol And my coyote puffed blue at first, and it was the tune (100k on it, give or take a few thou)

These 4.6 3v have always had a puff of blue smoke on cold start ups. Even when new. I remember thread after thread people asking. Even mine. And after 88k miles tons of performance mods, many road track and drag strip days, no oil loss on dipstick between oil changes (12 months) never gets 6k miles a year. Amsoil almost from day one.
I wouldn't worry too much on cold starts. Now if idling like at a red light and you hit the gas and see it, then we got worn seals.

My 4.6 has 185k hard miles on it and the only time I had those puffs was when I used when I used synthetic blend at about 15k. Mobil1 5w-20 since then and never looked back.


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It's not burning oil, it is cooler outside (probably,) that is fuel.

The engine will go 500,000 miles.

Stoenr said:

These 4.6 3v have always had a puff of blue smoke on cold start ups. Even when new. I remember thread after thread people asking. Even mine. And after 88k miles tons of performance mods, many road track and drag strip days, no oil loss on dipstick between oil changes (12 months) never gets 6k miles a year. Amsoil almost from day one.
I wouldn't worry too much on cold starts. Now if idling like at a red light and you hit the gas and see it, then we got worn seals.

Click to expand...

I have a 2005. There were hundreds of threads on the forums back then about this when the s197 first came out.

If you have oil in your exhaust you have to ask,, "how did it get there?"
You should never have oil in the exhaust--even when its new--But the nature of the PCV system puts it there. When the modular motors rev high there is alot of oil flying around the top of the valve train and it gets sucked into the intake and back into the engine. This is why alot of us run catch cans... Look inside your throttle body etc and look for oil, its ok to see dark deposits there but it should not be wet, if its wet that is where its getting into the engine.

Now assume you are not running your car like a rabid animal, just a daily driver on the road like everyone else and your seeing the blue smoke at startup, if its blue its not fuel.. Fuel smoke is grey, but its a darker grey.. Ok, you have high mileage, no big deal, but chances are your car has worn valve stem seals.. When the car sits at night the oil will weep down the valve stem and gets sucked in the combustion chamber at first startup...

Ok, if your driving and you accelerate and blow smoke its a ring issue,,,if your decelerating hard and get smoke then its definitely valve stem seals...

good luck...

The valve stem seals can be changed, but it's time consuming and you'll have to buy a couple of tools, but they aren't expensive. The catch is that you need to also check the valve stem to guide clearance, and you might just get in there and find this clearance is beyond the wear limit. If that's the case the seal change won't last as long as if the guide clearance was in spec. My $.02 US: drive it and monitor the oil level.

Mine done it since new!


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A tune with a CAI can make the issue look even worse. Mine used to do it intermittently on the initial tune. As I tweaked my tune, it no longer puffs blue on startup.
There is also a Ford recommended 'best practice' tsb on this issue. Ford claims it happens if you shut off the engine without letting it warm up fully. Crock O'shit if you ask me. Startup fueling is too rich.

When I fire mine up to move it in the driveway and immediately shut it down, it's going to puff white smoke at the next startup. Always has. It's the valve seals. Doesn't bother me much anymore.

Interesting...........

Just to add to this.....also don't forget these 3V's are notorious for oil vapor entry into IM thru PCV so think oil accumulation in IM plenum\runners during engine shutdown\cool off over time can appear to create the same scenario as bad valve stem seals during a startup. The older these engines get (or if FI the amount of boost as well), the more blowby increases, the higher % PCV oil vapor entry increases, the more accumulation increases inside IM plenum\runners....w\o a catch can installed to gauge\control the % PCV oil entry amount thru the PCV system (or remove the IM periodically & check it for oil accumulation....especially if you're still using the CMCV's) you'll have no idea of this info other than by checking the engine oil level periodically for level loss........thus only assumption.

I would wager this is far more common an issue than bad valve stem seals are w\ these 3V's........

The rest is for informational purposes..................

What Juice posted is also a factor as the OEM cold start fuel adders (which uses MAF\IAT & ECT to determine any extra fuel needed above the OL fuel table mapping during a cold start) in tune does tend to over do it on occasion causing oil wash off cyl walls thus puff blue\black\white smoke on startup at times (well known issue covered extensively on the HPTuners forums Ford tuning sections) which can be aggravated if a restart occurs right after an initial cold startup then immediate shutdown.....or when aftermarket camshafts are used w\ the OEM cold start fuel adder settings in tune (setup to the OEM cam profile). Don't know if this is better setup in Copperhead or later Ford PCM's but in Spanish Oaks PCM's this is a real thing. FYI, I got w\ my tuner back on 12-27-19 & had him to datalog my car during an early morning full cold start w\ these Lunati VooDoo cams & had all this readjusted to work better w\ these cams then recheck all else on the dyno afterwards (the only way to do this right & needs to be done during the coldest time of the year to dial it all in since Ford didn't map the cold start fuel adders in OL so a historgram can't be setup\used to easily tune it & these Lunati VooDoo cams weren't as well versed thru out the tuning community so no prior gathered\saved repository cold start fuel adder tuning data exists....). So needless to say, it can be a PITA to get right so most dyno tuners just leave this part alone......another area where remote Ford tuners\tuning have\has an advantage over dyno.....if the customer takes the initiative to get the full cold start datalog info at the right time & temp delta for their operating area(s) before sending it in.....

Also, if you're running a FPIM (rep of an open plenum located above the engine cyl head valley area & IM runners), it can aggravate the PCV oil accumulation issue inside IM worse than the OEM IM (know this from 1st hand experience) due to plenum design\location (OEM IM plenum is located in engine valley below IM runners which absorbs\retains more engine cyl head heat in IM plenum area thus doesn't allow PCV oil vapor to congeal as easily thus will stay suspended in airstream longer while running so will tend to accumulate less internally but can still puddle in IM plenum\runners depending on severity of PCV oil vapor entry once engine is shut down & cools off. The FPIM plenum is located above engine valley & runners thus overall cooler intake charge air vs the OEM IM--good for increased air density thus HP\TQ--but also causes PCV oil vapors to congeal more readily thus drop out airstream & collect more inside IM while running as well as during engine off\cool down so is more prone to puff blue smoke on initial cold startup than the OEM IM......also not so good for cats either.....just saying).

There are always cons associated w\ any pros in engineering design......

Keep this in mind if you're using an IM that has the plenum located above the engine valley w\ these 3V's (or even Coyotes for that matter) w\ a closed loop PCV system design in use. There's more than 1 reason why the OEM IM plenums\runners are designed the way they are w\ these Ford Modular engines.........

My 2 cents........

In the copperhead pcm, once I fixed the drivability issues I was having, it also cured all blue smoke on startup. And mine was embarrasing at times. And no smoke other times. Now its no smoke on startup even if I shut it down after backing out of the garage.

I think we can all agree fords go around backfiring and burning oil. Its embarrassing. Only 3900 for an electric motor, I might go with that.