What is this leak?
 

Doing some maintenance on the car this morning and wanted to clean the motor. I found this oil residue on intake tube. What could be causing this leak, what does it affect and before I start tearing Parts off. I need to know if I need to order anything first.

ADDENDUM: I removed it, cleaned it up and there was oil inside. Is this have some indication of the AOS?
Thanks,http://986forum.com/forums/uploads02...1476722770.jpg

The usual culprit of oil on the outside of the intake tube is from the hydraulic steering fluid overflow pipe - that's the reservoir located just behind the intake @ 11 o'clock in your photo.
Check the level and only use Pentosin CHF11S or CHF202 hydraulic oil to top up.

Oil in the inside of the intake tube can mean a failing AOS - check for oil again in say a thousand miles. Can you remove the oil fill cap OK with the engine hot & idling - a failing AOS causes a vacuum making the cap (sometimes) difficult to remove.....

I have CHF 7.1. I wonder if that's the same as what you're recommending or if it can be used. This is what I have from my BMW. Oil cap removal it's no problem so I hope the AOS is not malfunctioning (haven't noticed any oil from around the aos) but I'm still curious as to why there's oil inside of it - there are two vacuum hoses that I need to find out where they come from. Noticed a little smoke at startup lately. Probably from the oil in the intake tube. (Wonder why there is no oil in the lower tube). The intake tube has no cracks or holes and all four clamps are holding well.

I have CHF 7.1. I wonder if that's the same as what you're recommending or if it can be used. This is what I have from my BMW. Oil cap removal it's no problem so I hope the AOS is not malfunctioning but I'm still curious as to why there's oil inside of it - there are two vacuum hoses that I need to find out where they come from. Noticed a little smoke at startup lately. Probably from the oil in the intake tube. The intake tube has no cracks or holes and all four clamps are holding well.

Pentosin CHF 11S is the one you should go for.

CHF 7 is the wrong fluid. It is not allowed to be mixed with CHF 11 S.

And please read the manual first before topping up.

Regards, Markus

Thanks for the info guys. I will check. I thought you could mix 7 with 11 but, evidently not. I never heard of a small block that big but , thank you small 'smallblock454'. Servus daweil.

I think you will always find some oil residue inside the tubes as some oil/air vapour will precipitate there even if the aos is functioning normally. Since you don't have a big vacuum problem at the oil cap and no great clouds of white smoke, I wouldn't worry too much.

The outlet hose :barf:from the AOS to the intake was broken, so now I have a new aos and hose coming plus a couple extra parts. Thanks guys for the info I really appreciate it. This thing is not easy to put back together. need three hands or more.