Does Full Synthetic cause "Leaks"?

[JCCADILLACMOBILE]

I hav heard some people say they use Full Synthetic in vehicles with over 180,000 miles and never had a leak. Others say they have had "Bad Experiences" with it.

The Newest Twist is -HIGH MILEAGE- Full Synthetic. Seems it takes Full Synthetic, which is supposed to have particles oo small it will leak through... and make it act like Conventional oil, in NOT causing a Leak? MaxLife Full Synthetic comes to mind

Im just asking because i think Valvoline MaxLife Full Synthetic 5w30 Year Round will be a good choice for me after the Rebuild... Im just wondering what OCIs i should do again. someone said 500 miles, that would be a round trip from Indianapolis to Ohio... then 2000 miles.. that would be a trip to NYC from Indianapolis, plus a week of driving.

What OCI should i go with after that? 5000 to 7000 miles? Thats not "Extended OCI" as its Synthetic, right?

 

[JCCADILLACMOBILE]

.. it seems like Synthetic LEAKS vs maxLife STOPPING Leaks.

is there a better Analogy?

 

[bullwinkle]

If you are getting a full rebuild including piston rings the break-in oil should be dino/conventional to help with ring seating, then after 500 miles use whatever you want-hopefully your rebuilder is using NEW gaskets! If you're just having the head done-and if that's the "Iron Duke" GM 2.5 overhead valve engine in your sig (no overhead cam/pushrod motor)-I personally would stick with MaxLife and just change it every 5K or so (if mostly highway miles)-that motor is one of the tougher ones GM ever built!

 

[Robenstein]

A good high mileage syn oil will not cause leaks. What it can do is clean out the gunk that had previously built up and plugged leaks in failed gaskets.

 

[dgee]

just use a high mileage synthetic
i changed over a 94 grand cherokee with 250,000 to a syn high mileage with no problems.
if you're not leaking with dino, chances are you're not going to leak with syn