Checked oil after car sitting for 10 minutes

As usual, Miroljub is correct.

 

I have never noticed any difference in pressure readings as a result in barometric pressure. Even assuming that it could affect your oil pressure reading (and I'm pretty sure it couldn't because I think the pressure reading is a relative one) the variation would be so small it wouldn't show up on the gauge.

If you're seeing pressure readings that don't seem reasonable the first thing I'd suspect would be the reading displayed in the car (potential gauge/sender/wiring issues). The ideal scenario is to compare the factory gauge to a known-good mechanical gauge and then go from there.

 

Yes, my mistake, was correct in my mind just didn't say it right

When I start off cold the pressure is 100 or even higher but as oil heats and thins, drops to 70.

My car is normally at 70 under power (cruising)

 

Not Correct. How to check is in 355 owners manual page "B11". Many drysump Ferraris have this sticker right from the factory next to the oil tank.
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Carl, I realize you would debate with me how wet water is.....

I see you did not quote Tim or anyone else that agrees with me - But, I know how you operate

Here are the WSM procedures for the 360 and 458. Yes, I know we are talking 355 but it's the same concept.
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Checking at idle with the car running isn't that easy?

Oil is being shot around the oil reservoir, its fluctuating, splashing on the dipstick, etc. I suspect that with the car running, the oil level will read higher than it actually is. I could never get a clean reading with the car running (testarossa or 930)...

 

It is not about you. You are giving wrong advice that can damage people's Ferraris.

This is the 348/355 board not what you posted. OP has 348

355 owners see manual page B11

348 owners see owners manual B10 This is photo of the page from the manual. I am not making this stuff up. You have to do what the engineers designed for each model.
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At least it's not a cambelt change debate LOL

 

Carl, the one thing you are correct about is that I did not realize the owner has a 348 (that's my fault for not looking but also a common problem with mixed model sections).

Is the 348 a dry sump? If so, I stand by my statement....

And, if it's not about me, why are you not getting all over your fellow stooge (who is a friend of mine) or others?

Yep - we know how you roll

We also know the the manuals have zero mistakes and all the original fluid specs should be adhered to even if you can no longer get them

 

What kind of dry sumps? They are all different. Ferrari stated specifically to do it with the engine off on all models prior to 360 for a reason. The oil return is located such that it will spray oil on the dipstick.

Do it the way the book says. Assuming the book is incorrect with no supporting evidence is ignorance defined.

 

That did not work with my professor when I took that test in college...

 

There is what you are supposed to do, and the real world...

I remember when I was buying my testarossa (when they still did pre-purchase inspections!) I asked the dealer to do a leakdown "hot." As that gives the most accurate numbers.

He looked at me like I were an alien...

I get it. No way I am working on a hot motor either... But that's what the books say is supposed to be done...

Check the oil level with the car running? Hmmm... doesn't that cause oil to spray all over your clean engine bay?

 

No.

 

Thanks for weighing in, Brian.

In general I agree that it's wise to stick with factory recommendations but I've checked it both ways and haven't noticed a difference. It's quicker/more expedient to check it at idle but I'll try to make certain I follow the manual in the future.

Have you noticed any benefit to keeping the level toward the higher or lower end of the scale or is anywhere within range all the same?

 

Oil expands and contracts a lot and oil tanks are designed tall and narrow for a reason so the level will change a lot. A little low is never a problem. A little high often is.
I check oil temp with a hand held thermometer (the oil temp gauges really shouldn't be heavily relied on) and shoot for the middle of the range on the stick with 180 or more oil temp. Shoot the beam straight down and get the highest reading if you cannot look in there at the same time like a 355. Checking right after a good drive is a really good time. Then you know it is hot enough.

 

Thanks very much, Brian, for sharing your expertise (and not just in this thread).

 

Brian, help me understand why on a drysump too-little is better than too much? In a wet sump, with too much oil the crank beats the oil and aerates it, causing decreased lubrication. But, with a dry sump, that doesn't happen, right?

With a dry sump the oil tank is more filled, and the oil could overflow into a catch tank or into the breather/intake...

What am I missing?

I ask because I am tracking my 930 which is also dry sump. Some guys say to run it mid dipstick, some say to run it at absolute full...

 

What he says. Not really too hard to grasp.

 

Not Brian but you almost there. When oil is overfilled you suck in oil and overwhelm the PCV air/oil separator. That causes all kinds of problems from reducing the octane of the mixture to fouling and intake valve increase in deposits to hydro locking a cylinder when lots of oil flows. I got lucky last month racing at the Runoffs at Mid-O. I got black flagged for smoke and oiling the guys behind me. I had a PCV failure and crank pressurization that put 3 oz of oil in my catch can per lap! Getting black flagged probably saved my motor.

Regarding the 930 you need to talk to more Porsche people to find out the race fill level. High G turns, oil level, baffling, oil pan design, oil pressure are a few things that change the scavenging ability from the pan. Take one simple issue high G turn pushing oil away from the oil pickup = oil starvation= short engine life. Granted that's more likely with wet sumps then dry scavenging but it can happen. C7 Vette racing the Owners manual tells you to overfill 1qt and that is a drysump motor. That 1 qt over philosophy right from GM goes back to the wet sump C5 vette and is printed right in the owner's manuals. If you can't get a straight answer from a knowledgeable P guy then put a pressure sensor on the 930, race it and data log it. And remember as you get faster and have stickier tires pulling more G's and can modulate the rpm closer to peak power and torque in the higher RPM range you may need to gather new data because your new skills are changing the engine requirements. So if you are really only 6/10ths of what a 930 can do you might be fine at max level. When you get to 9/10ths of what the 930 can do you may need to run more oil.

 

Most of the oil in the tank will slowly flow down into the dry sump after engine switch off and flood the (very shallow) crankcase so there will be brief "beating" of the oil on the next start-up. But I don't think this should be of any concern as it is very short and will not turn the oil into "milk shake". So, I don't think lower is better than higher (within the min-max range, of course) as far as this is concerned.

The main function of the oil tank ("surge / buffer tank") is to provide a positive suction head and a steady volume of oil, without any air bubbles, to the main oil pump and to prevent oil starvation in turns or on hard breaking when the oil is forced to one side of the tank. If the level is allowed to go lower, there is a risk of air bubbles forming in it all the way to the bottom which could be sucked in by the main oil pump. The incoming oil delivered by the scavenger pump is full of air bubbles which need space (the height of the oil column in the tank) to dissipate. I would therefore keep the level in the tank closer to the "max" as, with the oil at lower levels (closer to the "min") the risk of air bubbles not having enough time (space) to get out of the oil and being sucked in by the main pump, and the risk of oil starvation due to braking or centrifugal forces, increases. If racing, certainly go to the "max".

 

Sounds nice but not really correct in the cars in question. Not sure what you are talking about, could have sworn this was the 355 and 348 thread.

 

930 is a different car. I guess some here still don't get the fact we are discussing 355's. Porsche conversation is better done on a Porsche chat room.

 

What I know is I have been successfully checking oil at idle with no issues. YMMV