I don't want to insult anyone's mech skills but thought I'd mention this... I've had dry sump Porsche's for some time and after filling the appropriate amount of oil I've been 'trained' (by pro wrench's) to wait 15/20 min before start up for the oil to migrate to the oil pick up. Not sure what GM recommends as I am comparing two very dif systems.

 

Maybe something unique and useful to Porsche. I’ve fired my Z06 after filling the tank on an oil change - which probably took at least 10 minutes from start to finish and I had immediate oil pressure. I’m not even sure where the oil PSI sensor is, but it came right up. On some of my other cars, I crank the engine with no fuel a few times to prime the system.

 

When I was checking it during break-in, the manual specifies always done with the engine running as you are about to refuel. I'd imagine that if you followed the same procedure, it should meet the standard you pointed out unless you live literally next door to a fuel station.

 

This makes no sense. To check oil level in a Porsche with dry sump, you need to start the car and get it to operating temperature. When the engine is running there is very little oil in the engine case. The oil pump scavenging pickups remove the oil from the bottom of the engine case quite efficiently. If anything, you don't want to let the engine sit for 15 to 20 minutes because, at least of the air-cooled engines, the oil could drain back into the case. This would result in much more oil in the case than when the engine is running. This is the main reason the oil level is checked with the engine running and warmed up.

As far as oil being present at the pick up for a start. There is no need to wait a while. Oil is always present at the pickup unless it is the first start after the oil has been drained.

Note: I have worked air-cooled 911s since 1978 and have owned at least one since 1992. I currently have an air-cooled 911 race car.

 

After an oil change... there is a sump of sorts in P car and when you change the oil you know it as you drain both...and that is where the pick up is. That is what I am speaking about.... after an oil change.

"As far as oil being present at the pick up for a start. There is no need to wait a while. Oil is always present at the pickup unless it is the first start after the oil has been drained."

That was the whole point of the post ....after an oil change. Perhaps I assumed too much...."and after filling the appropriate amount of oil "....

Next time I'll spell it out. Can't imagine this confused some. Like you'd sit in the car waiting for what on a non oil change day?

 

After an oil change where you drain oil from the engine and the dry sump tank, you put oil in the dry sump oil tank. You don't need to ad oil to the engine. There is a line coming from the bottom of the oil tank to the bottom of the engine where the oil pump is fed oil. That is not part of the "sump" where the scavenging pickup(s) are located. If there is enough oil in the external tank, gravity feeds the pump and there is no priming that needs to be done. When I said there was no oil at the pickup after an oil change, I was talking about the scavenging side of the pump. The feed side has oil ready to go as the oil tank is well above the oil pump pickup at the bottom of the engine.

The only time you have to worry about getting oil into the engine is after a rebuild. You want to turn the engine over without starting it until engine oil pressure registers on the gauge.

 

That is a different set up than the P car but I do believe GM also recommends a 5 minute wait for the oil to migrate...it was 10 and they dropped it a bit. That was the point. OTOH, never mind.

 

Thanks for the Porsche diagram. Not familiar with the Porsche engine or "requirement" (did have a 6-cylinder, 2.7 Liter Air Cooled Boxer engine back in the day but not a Porsche!)

First the oil that pressurizes the engine comes from the dry sump tank. The main oil/air pump in the crankcase sucks all oil and a lot of air into the dry sump tank. In fact in race engines, they create a near vacuum, so the crack/rods have less drag rotating than in air. Can be a significant hp gain. In fact, the C8 Z06 at high rpm with its multiple scavenge pumps creates ~11 psi vacuum or ~70% of zero air in the crankcase.

Had two C7 dry sumps and they both required waiting 5 minutes BUT not more than 10 to check the oil level in the dry sump take (done with the engine off.) Had nothing to do with needing to wait to start the engine. You had to wait 5 minutes to check the oil level as the added oil passed through the tank baffles. If you did not could get a false high reading. However, if you waited more than 10 minutes excess oil would flow back to the crankcase (probably past the scavenge pump gear) and you'd get a low reading. Did all my own oil changes wonder how many techs followed the GM requirement.

For a test I checked the oil level after the C7 sat for a day and it was below the tip of the dip stick >6 quarts low. But there was always sufficient oil available to pressurize the engine, no need to wait to start the car. Some folks said they could hear the oil flowing to the dry sump tank if the car sat for a ~day before starting.

Here is a pic of the C7 pumps. Two pumps with different sources of oil!


Don't know if it adds anything but never heard or read about waiting for the oil to drain into the integrated dry sump tank. This is a cutaway of the tank. Those 1st few quarts would be at the bottom where the engine oil is sources from pretty quickly!

 

The oil change procedure for the Stingray does not include any instruction about waiting "for the oil to migrate to the pick up." The Stingray drain plug is long, and has two separate gaskets - it drains both the oil tank on the front of the engine, and the engine oil pan. Oil is added to the oil tank on the front of the engine. The pickup is in the oil tank - it is fully submersed when the oil tank is filled. There are other pumps that scavenge oil from the pan and engine valley. No recommendation to wait for oil to migrate anywhere though.

Once the tank is filled, the engine is started, and the oil level in the tank is checked and topped off as needed, after the car has warmed up sufficiently.

 

Well thanks, you've saved me some time....great illustrations too. Sorry for the bad information as I was simply attuned to older Porsche dry sump systems.