What's an expected "spread" on hot vs cold oil level?

Measuring the oil level on a cold 308 engine (without have just run a bit) is meaningless and hugely variable -- because the amount of oil that drains back into the wet sump a long time after shutoff is not the same for all 308 (due to different internal clearances, different oils, different stopping place of the crankshaft). To summarize:

Measuring cold without having just run = meaningless
Measuring cold immediately after just running = will measure a little low as the oil has not expanded in volume
Measuring hot immediately after just running = proper measurement

 

My 83 308 showing between the lines cold will be overfilled when hot and 15 minutes after shut down.

 

In the 80's when Ferrari had issues with oil consumption in the 308s during the warranty process to determine exact consumption Ferrari had us going through a fire drill that took a couple of hours. Using the dipstick to determine it was just not part of Ferraris plan, they knew how variable it was. One way and one way only to measure it, hot. And even then it can be inconsistent depending on a few variables.

 

You will drive your self crazy trying to quantify oil levels. Many have tried, all have failed, it's not a Toyota.

The best you can do is consistent conditions when looking at the dipstick, something like always after the car sits overnight or within 5 minutes of driving the car. The best way I have found is when doing a routine oil/filter change drain thoroughly (like let it drip while you eat lunch) then refill with the factory specified amount of oil. Drive the car enough to thoroughly warm the oil (Ferrari conveniently supplied a gauge to monitor that) then park the car and let it sit for 1-5 minutes before checking the dipstick. Remember how long the wait was and always wait the same amount of time thereafter. The same could be done with the engine always stone cold. This should be after determining a level "hot" then read the dipstick again when cold and note the changed level on the dipstick, it will be a bit higher after a long time for the oil to down into the sump. Some people, myself included, find that the dipstick consistently read LOW for several checks and I ended up adding a qt or 2 (yikes!) to get a "full" reading. If you do have to add oil only add 1 qt. then do another couple of cycles checking the dipstick before deciding to add more. At the next oil change adjust the amount of oil by the "extra" that you added and always use the total amount as your baseline thereafter. Some, most, almost all Ferraris consume some oil either burn it, leak it or both. Using consistent conditions when checking the dipstick should keep you from overfilling or running low on oil. It's far better than chasing that illusive ideal dipstick reading.

 

The 328 manual is amusingly specific about when to check:

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I found a value of 0.0007 /°C for the thermal expansion coefficient of engine oil. So, for 10L of oil at 20°C that is heated to 80°C, you should have 10.4L, or roughly 1/2 L extra volume. Not much, but enough to bring you over the top fill line if you are near it when cold. Best to stick to the owner's manual for measuring...

https://www.engineeringtoolbox.com/cubical-expansion-coefficients-d_1262.html

 

Well...when I bought my first 328 (that I still have) in september 2008, believe it or not, I read the "Owner's manual". Have always checked the oil level as per the manual's instructions since. A good, long drive; stop the engine, wait 15 minutes and check the oil level as my dad taught me to do: get the dipstick out for a first time, don't look at it, just clean it; then back in, out again, and now read it; and write down the oil level and car mileage.
(The car doesn't burn any oil at all, by the way)

Rgds

 

This is really too easy...........these are Ferrari's for Gods sake. There should be some intricate procedure that requires complex mathematical calculations, and measurements. Reading the owners manual............you gotta be kidding!

 

It seems backwards to me to choose the amount of oil based on a mass produced and perhaps inaccurate dipstick.

I've always baseline my cars by doing a complete drain and refill with the factory specified amount of oil, then changed to the dipstick markings to suit.

 

The problem with this is that you can never drain absolutely all of the oil out of an engine -- i.e., a newly assembled "dry" engine (with no oil ever having been in it) will take the specified amount, but an oil change will use somewhat less to get back to the same level. The OP only needing 8~8.5 qts for a 308 oil and oil filter change seems perfectly reasonable to me (and matches my previous 308 experience). Are the "new" marks that you add to the dipstick always higher than the factory dipstick marks?

 

Hmmm...I think there is too much worrying. Check the oil as per the manual and let it go at that. OR, check the oil per the manual (hot) and the next morning check it again (cold). That will give you the reference for either hot or cold checking from that point on.

 

Steve-

No, not necessarily higher. It totally depends on the machine. Mind you I've not yet tried this on my 308, but I've done on many others, most recently my Jag E-type. I simply won't trust the 'calibration' of a dipstick on a 40+year old car with unknown history until I verify it myself. My list of previously owned old sportscars over the last 45 years is long, btw, so lots of experience with bent, incorrect, or missing dipsticks.

 

Can you explain the last part to me? How would the crankshaft position affect how much drains back to the sump or how it affects the oil dipstick reading?

 

This is a first for me also that someone comes up with this, can we end this please just read the manual and do the Oil change

 

Don't disagree that we spend way too much time and effort on this . Just that how much oil drains back down into the wet sump from the engine internal passages/hoses/cooler depends on the various clearances between the parts and oil hole passages (and whether or not the anti-drainback valve in the oil filter is working well), and those clearances are not always exactly the same for every position of every rotating component (especially when not running).

 

Check the oil on the dipstick. If it's low, add some. That's pretty much it.

 

This is too complicated for me. This is why I haven't changed the oil in my 308 in 38 years.