Low Oil Pressure

The oil used in most Ferrari's is synthetic oil it's very thick that's y it seems like the pressure is low but it's really not. If you use the regular oil, which is much thinner, you will see your oil pressure much higher but I wouldn't recommend it.

 

My oil pressure readings are lower since I switched from regular to synthetic oil in the 348.

Edit: My pressure does rise though with higher RPM. From saw1998's last post this looks like something different.

 

If your pressure is a little below 70psi when car is warm this is normal.

 

Did you just have the oil change? If you did, the first couple days you will see that drop since the oil is so thick. I had my 30k serice done this year and for the first week my oil pressure was low like your are describing in your situation. Now it is at around the 35psi or higher when warm.

 

Something is not right, that is too low. Attach either an accurate mechanical gauge or a known good sender. Your pressure is dropping much sooner than it could possibly be from warming.

 

Don't go throwing away money on spares and electrics. Check this out then make your mind up. Sorry for the long post, but this way you can follow the reasoning and then make a better informed decision.

Assumption - oil level is correct to start with.

The hypothesis:
You DO get a pressure reading which varies with rpm, so when the engine is cold having a lower pressure indication tells you the oil is running freely and lubricating the engine at the most critical moment - when it is cold and unprotected. (You get a spike in the reading as the oil needs to be pressurized beyond its "stiction" to start moving, then the inertia takes over and helps it along).

As the engine warms up, the polymers unwind and keep the oil from thinning out too much so the oil film does not shear and it sticks itself and the hot surfaces. In this mode, the oil pressure can drop further at idle (the base oil is thinner when hot, so it flows more, thus causing lower pressure - remember, lower pressure = higher flow speed) The key here is getting that 90-100 PSI (60-70% of the scale) at 6000 RPM. If you do that you are fine with a nice clean engine and a good oil. If not, then turn it off and you have a problem in the oil system.

So here's the reason. More modern oils flow much better, especially when you are going to fully synthetic. If you put a 5W40, you are putting in a 5 weight oil which does not thin more than a 40 weight would when at 100 deg. C though added polymers. A 5 weight oil has a multiple of viscosity than a 10 weight oil (flows better through an orifice) thus lower pressure through a given constant orifice. A 0 weight even more so. So these oils will flow better when cold, and faster flow = lower pressure. Flow = lubrication, so you can get better lubrication with lower pressure.

Lower oil temps are a blessing as all the non metallic part in the engine tend to wear less when less hot - I am talking LESS hot though, not COLD!

The evidence / observations:

My mondial t was meant to run on Agip mineral 10W40. With that in it (for the 10 minutes after I bought it) and when well cold I used to get 50% scale (I'll use proportions as mine is in BAR and not PSI), which would then reduce to 15-20% once warmed up. I'd get the 70% reading at 6000 rpms though. The oil temp would hit 50% quite regularly.

I did a nice oil change, using 0w40 "Mobil1 with all the bells and whistles and a picture of that McLaren race driver with a tan", then I'd never get more than 10-15% of pressure at startup and it would stay like that throughout the heating cycle. When on the move, I'd still get 60% at 6000 RPMs. The Oil temp never went past 40%, even on hard runs.

I changed oils again to a 5W40 "Shell helix bells and whistles with a free Ferrari Hat" and I'd get the same 10-15% (higher on colder days, lower in hotter) and still get 60% at 6000 and lower temp readings 40% as the usual.

I was due an oil change, so I did a test, by adding a bottle of Luca's oil additive (thickening agent), and the pressure now is at 40-50% when cold, then stays there until well warm to when it drops to 20%, but I still get the 60% at 6000 rpm. (I did the change 5 days later to the winder 0W40 oil)

The proof:
I have put 9000 miles on my Mondial t this year with a 0W40 in winter and 5W40 in summer. My oil temp barely registers when warm and idling, I do have the full 60-70% reading at 6000 rpm. The puppy runs perfectly and the oil comes out relatively clean at the changes. Incidentally, I don't have more oil usage than the user manual suggests, so no, the thinner oil does not get past the rings....

P.S.
The 6000 rpm test - the plumbing in the system is designed for a maximum throughput. If we all use oils that are rated <0,5,10 etc>W40, the oil system will always produce the same pressure for a given rpm (6000) if the oil (40) and temperature (80 deg. C) are constant.
P.S.S. That's why you want a <0,5,10 etc>W50 (or higher) if you're going to kick some butt and get those temps really high - you don't want low pressure at high RPM!

 

I have the same car as the OP, using the same oil and presumably filter. Yet my oil pressures are much higher...and seem to coincide with my two friends that have identical 355's. Granted you are in Texas, we are in Seattle, but even on a warm summer day I would not see the pressure drop you are seeing, until at least 10 minutes of light driving. I just cannot see a drop like what you are seeing after 30 seconds, except on an already warm engine.

As an example, my typical start up pressure puts me in the "one o'clock" position on the oil pressure gauge. After a 5 or 6 minutes of light driving it will drop to between 11 and 12 o'clock. Once fully warmed, (12 minutes or so) it will drop to 20 to 35 psi on the gauge at idle.

But as my friend Bighead Dennis says.... "I could be entirely wrong on this"

 

Scott,

Is your car a F1 or a 6 speed ???

 

Scott,

I asked because the oil pressure gage is in a different location on F1 shift cars.

Pop the insturment cluster pod off and check to make sure the contacts (brass nuts) on the back of the gage are secure. I have had similar issues with cars and corrected it by tightening the (loose) contacts.


Hope this helps,
Adam

 

When I plopped a 1 liter bottle of lucas synthetic additive into my oil tank I think it was a synthetic 50 weight base), the pressure went up from a standard of 10-15% of the gauge when at warm idle to 30%. Cold idle was at 50%. The bottle cost me GBP 18. It is a cheap test. It will not screw up your existing oil as it is a synthetic mix, and diluted 12:1 will not be of issue in terms of chemical stability.

Marco

 

I had a similar issue with my 911. After lots of work, it was determined to be a faulty oil pressure sending unit. BTW, the error light will usually be a separate circuit from the feed to the gauge needle.

 

+1 to this answer. I had an issue very similar to yours but when the gauge was reading low I tapped on the dash directly above the instrument cluster and it sprang up to the normal value. Believe me, there are few things as bone-chillling as starting your F355 and seeing 0 PSI on the oil pressure gauge! Fortunately, the low oil pressure light was off so I figured it had to be the gauge or the contacts and not a potential 8-cylinder hand grenade idling just over my shoulder. I cleaned the contacts and all is fine now.

Wallace

 

How is the gauge cluster removed? I didn't see any clips of screws.




Darrell.

 

Hi Darrell, there are 2 screws at the base of the cluster ether side of the steering column, remove those 2 screws and you can lift the cluster up to see the wiring underneath. Hope that helps.

James.

 

+1. I would recommend lowering your steering wheel first (release the clamp below) and place a towel over the steering column to protect from scratches. Good luck Darrell, and please report back.

 

Thanks guys. I'll give it a check tomorrow. The temp gauge just stopped working the other night. The red "dummy" light is working and the connections at the sender are solid. Hope it's just a loose wire.



Darrell.