996 C4S smoking on start up from cold, I'm worried

Hello, I am new to the forum since purchasing a 996 C4S 2001/2 earlier this year. All has been great and I love the car to bits. The other day after being sat overnight I fired her up as usual and a fair amount of white smelly smoke came out the exhausts, (it wasn'y just condensation), and then about 5 seconds later it was just condensation. I really hoped it was a weird one off but it did the same thing later, less smoke but had only been sat 2 hours. Then this morning after a worrying sleep I fired her up and rushed to the rear to see what was going on. This time the smoke looked more blue a very small cloud but smelly and after about 2 seconds it cleared to just condesation. I unscrewed the oil cap this afternoon and there appears to be a mayonaisy looking gunk sat at the top of the pipe. Have you got any thoughts on the problem, do you think its the head gasket? The car has Gold warranty for another 11 months so that's one bonus.

Tosh!! Don't panic, it is unlikely to be as serious as you think. White smoke at startup (oily to the touch) is usually the sign of a failed air-oil separator. There are a couple of tests you can do to confirm it. The easiest is to start the engine, and try to remove the oil filler cap with the engine ticking over. If it is hard to remove (lots of vacuum) then that is an indication the AOS has failed. The other test is to remove the inlet pipe to the throttle body, and open the butterfly. If the internal surfaces are glossy with oil, it is definitely the AOS. The only other cause of smoke is more unlikely, and caused by scored bores. The main evidence of this is a sooty tailpipe on the left hand side. If both pipes look the same, then there is unlikely to be an issue. Mayo in the oil filler tube is very, very common, especially in this cold weather. It is just an emulsion of condensation in the long plastic filler tube, and oil mist from the crankcase. Absolutely nothing to worry about. Hope this makes you sleep easier.

Hi, Thanks for the post, I am feeling much better already. I had seen some posts about the AOS failures and wondered if this was the issue but felt with the gunk in the oil cap area it was going ot be the H/G. I am still slightly concerened because I am sure the garage I bought from had the AOS replaced before I purchased the car. Hopefully it's just a bad one that has gone again and nothing more expensive. It's weird because she was in the garage, (having the offside tail pipe braket welded as it had broke and was making aweful rattle when pulling off), only a day before this smoking started happening so I wonder if they damaged the AOS by misstake. I'll get her back down there asap and just cruise around for now. Thanks again.

Have you been keeping an eye on oil levels? Maybe after xmas get the bores inspected (camera down the bore). Either way if you have a proper warranty then you're covered.

I have checked the oil physically a couple of times and its got plenty in there. It's nice new oil as had a service about 1k ago. When I head out today I'll do the electronic oil check on start up and see it reads ok. Checking the bores is a good call. She didn't smoke at all when I fired her up yesterday after 48 hours stood.

One of the features of the flat six engine is white smoke at start up. Oil in the cylinders runs to the bottom of the cylinder, fire it up and you get puffs of white smoke. If yours is only smoking for a very short time then that maybe the cause. Cheers,

Hi There, I had the same problem. Smoke on start-up, espeically if I had started up the car the night before and put away in the garage. It did it every other time. This was just after a service where they had used 0w40 Mobil 1. I think you've got the issue Fred describes. I make sure the oil is one notch down from max on the oil check gauge. Drives me mad, but theres not much you can do. I have used slightly "thicker" oil, and it's only done it twice in three months. Dave

This sounds likely and obviously is a relief, had no smoke for a couple of days now so that's great. They did use the oil you refer to and I did the electronic read today, totally full. I'll keep an eye on the issue and with any luck all will be swell. Thanks everyone.

This is very common, all my porsche have done it - so long as it clears after a few seconds then its nothing to worry about. If it was AOS you'd notice white smoke under load......

But in my experience, it is usually a puff of blue/grey smoke, not white. A sure way of inducing this is to drive the car out of the garage, wash it, and put it away. Next start-up will create a puff of smoke. I found that using 5W-40 instead of 0W-40 made it a lot less frequent occurrence.