It' started after I switched to synthetic from dino.

should I switch back to dino to see if it goes away?

if so should I stay with dino? or is synthetic really that much better?

IMO it's worth a shot.

It's a leak, fix it.
It's not all that big a job.

Isn't that a common problem when switching from dino to synthetic? The thinner composition finds places to leak that don't leak with the thicker oil. I was just thinking along the lines of time and expense. I agree with Bill though if you wish to stay synthetic. What are the details of your engine? Recent rebuild? Mods? Mileage?

15k on 383 hi performance engine in my signature

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Doh!

1989 L98 Blk/Blk,Z51,J55,FX3,3.33,D44,Zf6 deleted built 87-700r4, 2100 stall, 383, Mahle flattops,Scat 9000 Crank,Rods 10.7, AFR 195 Streets, SuperRam, Comp Cams 280XFI 230/236, Crane 1.6RR, Doug's Shorties, LTx Catback! Passed CA Smog

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Only when there's crud built up from the dyno.

Run whatever oil you want, fix the leaks.

I am with Bill. Fix the leak.

It's an urban legend that switching to synthetic will cause a leak. All it will do is clean up the goo that has been plugging and THEN leak.

If your PCV system is functioning it should prevent most oil leaks above the oil line from ever showing up due to the slight negative pressure in the crank case. Check your PCV valve to make sure it still sucks.
Tech

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it sucks (PCV), the tuning in the past left a lot to be desire insofar as vacuum, finally got is dialed in after 2 years of "learning".

how can I increase vacume? rhoads lifters?

Vacuum is a direct result of cam profile.

It doesn't really matter how much vacuum you have. you just need enough to keep up with the blow by and a little bit more to pull some fresh air through the block to keep the oil from getting too watered down with fuel vapors. My concern was that you might have a little pressure building up in the crank case pushing oil out through the seal.
Tech

how do I fix the pressure issue?, fixing the seal soulds like a band aid

http://corvetteactioncenter.com/galle ... e/1985-l98-engine/cat/557

Is this close to your engine?
If so the drivers side valve cover has the PCV valve seated in a rubber grommet in it just behind the air pump. it should just pop out. At idle you should be able to feel it sucking. if not replace the PCV valve and check the tube, it connects to manifold vacuum.
The other valve cover has a breather port. It usually connects to the air cleaner side of the throttle body. If you pop it out at idle you should be able to feel a slight suction on the valve cover hole. If blow by gasses are escaping from the hole then either the engine is really tired or the suction side isn't working.
Hope this helps
Tech

oooh... I see some misunderstandings on what PCV does... Positive Crankcase Ventilation was one of the first emission controls placed on engines come 40 years ago.

The idea is simple, close off the internal engine vapors so that the gick doesn't just float into the atmosphere.

All the vapors, from combustion gasses to the vapor off the motor oil itself are captured and burned off. Fresh air is introduced, under vacuum pressure, to draw the gick through. When the PCV is blocked, the pressures can rise, creating leaks. Also, because engine vacuum is used, it can cause run-ability problems when an external leak is created.

Make sure all the vacuum lines are good and that the hoses that run the system are good. Oh, and the valve itself!

If you are running synthetic oil, it does not mix with gas in the same way dino oil does. It kind of encapsulates it and it gets trapped in the filter. The vapor isn't strong enough on its own to harm the oil, but during startup, the fuel that blows by the rings or what sits in the combustion chamber will do damage. And it is that which is captured by the synthetic oil, deposited in the filter and once the engine reaches op temp will ultimately get burned off.

Dino oil will simply break down over time, some fuel will get burned off, but for the most part, the fuel will bond with waxes and thin down the oil.

This is one reason why synthetic oils are really better. Oh, and just so you all know, the real difference between synthetics and conventional oils is the absence of the wax. Get rid of the wax, good things happen!

Those gasses are VERY toxic, and the act of burning them off has been very instrumental in clearing our air pollution problems.

okay will check all the hoses, after the poly hassle