Avoid Dry Sump Overfill, Read Your Owner’s Manual!
Corvette Forum member 3blackcars has a problem. I don’t wish to add myself to the pile of people beating on him for his mistake, but rather would like to make sure our readers are aware of this potential problem so they can avoid potential damage to their own Corvettes. If you have a dry sump car with an LS7 or LS3, you’ll likely want to read through the whole thread and then follow it up by reading the entire owner’s manual to your car.
You see, 3blackcars had a rattle on startup after letting his Z06 sit for a few days. He was concerned and checked the oil level of his car’s reservoir, which of course read that it was low. Without investigating further, he dumped a couple quarts of quality motor oil into the reservoir and promptly fired up his precious ‘Vette. For those of you who know, it’ll come as no surprise that the car smoked like a diesel, shook like an earthquake, and had a nasty hiss. Immediately shutting down the car and re-checking the oil showed that the reservoir was now seriously full of oil.
If you’ve ever read your owner’s manual, you’ll already know that you’re supposed to check the oil level of your dry sump Corvette after the engine is warm. The proper procedure is to warm the car up to operating temperature (either by idling or by driving) and then shutting it down and waiting. You have to check your oil level at least 5 minutes, but no more than 15 minutes after shut down. At that point you can determine your proper engine oil level.
3blackcars’ engine was “rattling” on startup because the hydraulic lifters had emptied of their oil by sitting for days, and they do make a rattle until they’re filled again with oil pressure. This is normal and does not need any investigation. The other problem is that the same thing happens with your oil sump, as some of the oil will drain out of the reservoir and fill up the sump and crank case. Once the engine is fired up, that oil is quickly returned to where it needs to be and the oil level of your reservoir is inflated back to normal. By adding two quarts to the reservoir, when that sump oil was pumped back up, the tank was now way too full. Then the vacuum system sucked up some excess oil and it found its way into the intake and down into the cylinders.
Check out the thread, follow the directions in your owner’s manual, and don’t blow up your dry sump engine!