I've had my '95 F355 now for a couple of years. Everything seems to be fine except I've noticed that my oil pressure always seems to be high. When cold, it will be around 120 (70 is the middle reading and 140 is the max reading on the gauge). Once up to temperature, it will run around 105 (halfway between the 70 and 140 markings). Is this normal? The car seems to run great otherwise. I use Mobil 1 15-50 synthetic, with the factory oil filter. I have asked other F355 owners (non- '95's) and there cars don't run this high. Could this be a '95 model year thing?
seems very high to me, mines a 99 and its about 30pc less pressure than yours. Anyway, get rid of that mobil 1 and put in the suggested shell stuff !!
Oil is too thick. Try a 10W40 synthetic. I have been running 10W40 at the race tracks in Texas with good success (in 105 dF heat). This oil (same brand as the 20W50 stuff I used to run) starts easier, and even runs at the track with lower temps than the thick stuff. When I ran the 15W50 stuff, I had higher temps and higher pressures on the street, and when comming off the track I would have lower pressures and higher oil temps than on the lighter weight oils. 10W40 weight works so well, some time this year I am going to try 0W30 ro 10W30 at the track in the Texas summer heat. Alternately, there is a spring that controls the oil pressure. There is an updated spring that lowers the oil pressure 10 PSI or so.
I watch both oil pressure and oil temps both on the road and on the track. My car runs at lower temps and higher pressures on the track with lower weight oil under comparable outside temperatures (105 dF). Lower temps imply either that this oil disipates its heat better into the air than the heavier oil (doubtful) or that the engine produces less heat due to easier pumping of the thinner oil (probably). The on track oil pressures tend to indicaste that minimal/zero additional friction has occured due to the lighter weight oil. The combination of lower temps and higher on track pressure indicates that the lighter weight oil is BETTER at doing what oils do than the heavier stuff (which I used to run). Starting easier, and getting up to pressure sooner at cold start are an added bonus.
Possibly the guage or oil pressure sender unit may be at fault...have the pressure checked with a mechanical guage remotely at oil pressure switch.
i had exactly the same problem with my '95 355. i am told by people who really know not too worry about it but anyway i had the oil pressure relief spring reduced in size too bring the oil pressure back to normal. My car has done 50,000 miles with this high oil pressure with no problems by the way. It has nothing to do with the sender unit nor the guage. Just one of those f things
I had a similar problem with my 328GTS. Oil pressure on these cars IS adjustable via changing the spring as mentioned previously. Changing the viscosity of the oil will have an effect as well. (you are using a higher viscosity oil than Ferrari recommends). Using the correct viscosity oil MAY bring things into the correct range, or at least closer.
