Killjoy7

Hi guys,

New Z owner here and could use some advice. I just purchased an '08 Z06 with 14k miles today and in the course of inspecting it, i noticed a bunch of oil on the bottom of the sump where the drain plugs are. It turns out the gentleman I bought it from had taken it to the dealer for an oil change and they filled it with 11qts of oil! Said it right on the dealer invoice. crap. I had flown down to buy and drive the car back. The owner had not noticed anything and had driven the car about 200 miles already without noticing anything wrong. He even got it smogged during that time.
Anyway, We drained the excess oil (did't look like 3 qt--maybe 1.5) and got the level back to the middle hole on the dipstick using the proper oil checking procedure. We cleaned up the oil and i drove the car 300 miles home with the agreement that I would have it checked out by a dealer here for any damage. The Z runs fine, no smoke or weird stuff. I jacked it up when i got home and no further oil was on the sump.

Do you guys think any long term damage could have been done? I'm not familiar with the dry sump system but I'm trying to figure out where the oil on the bottom of the engine came from in the first place. is there a vent or overflow up there? could maybe a seal have blown out?

No new oil has leaked so it's a bit of a mystery. Any knowledge would be appreciated.

thanks

User Omega

They very well could have splashed oil from a drain pan after dropping the oil filter during removal. If you had blown a seal you would see oil still leaking. I am unsure if the engine could have been damaged in a way that would show up later in its life from this event. From what I am reading they usually smoke pretty bad after doing this and its from oil entering the intake manifold. It can cause severe damage but I would seem to think that if it were never smoking that no oil entered the manifold.

This is the exact reason that many of us change our own oil. Too many times you read this kind of story.

GOLD72

Anyone owning an 06 to 08 LS7 has to really be on guard for overfilling by others due to GM increasing the dry sump tank for MY2009 and later.

BRISLS1

Can you even put 11 quarts of oil in the fill hole during the change? I remember I over-filled mine once, and just had to wipe the tank clean and spray off the driveway. And I don't ever even buy more than 10 quarts at a time, because I get the 2 big 5 quart jugs, or sometimes buy 3 individual quarts to add up to 8.

Sounds crazy that you would even fit 11, unless the car was running?
Maybe they billed you from a manual that was for a later year, and didn't measure the actual fill.

I agree with USER OMEGA; probably harmless spillage.

pewter99

usually they underfill.....thats why I DIY oil changes 99% of the time...the rest I take to my buddy Joe at Powertech Performance...his guys know the differences between LS1 / LS3 / LS7 and the specifics for each year. If you insist on going to the dealer see if you can either provide the oil and filter or make sure they note what you need on the work order so as to not take chances.

Unreal

Check the air filter and throttle body for oil. Probably not a bad idea to pull them for a cleaning either way.