355 Oil Temp

My oil temp is at 190 most of the time. I use Mobile 1 15-50 and live in hot sunny Southern California. Both fans on my 1995 355 turn on at the same time and turn off at the same time.

 

Oil temperature while interstate cruising: 185dF at the thermostatic limit
Oil temperature in city traffic: 210-215
Oil temperature backroad corner carving: 230-240
Oil temperature on road race track: 265-275

Note: cars tend to last longer with oil temps above 212dF as this boils the water vapor out and neutralizes the acid blowby from normal combustion.

With a standard synthetic oil (5W-40) you should have no worries until the oil temperature gets above 265dF, and you should hold back on running the snot out of the car until the oil gets to at least 140dF.

 

How is that possible given the differences in the two control systems ?

 

I used to have a 98 F355 F1 Spider which didn't have an oil temp gauge. I now have a 98 F355 GTS (standard 6-speed) and have been paying attention to oil temps. Where I live, the climate is high 80's to low 90's right now. I've driven the car only 3 times. Each time driving pretty spiritedly; seeing 7krpm+ as well as ripping it down the highway.

My oil temp gauge displays 265df and never goes any higher. I was worried because the way the gauge indicates, the 265 mark is very close to the red zone. I'm hoping that perhaps the designer of the gauge was simply running out of room, and that I still have another 55df degrees to go before it's too hot.

Also, my spider oil pressures used to run pretty high. Above 70psi easily when driving hard... sometimes when simply cruising at 80mph on the highway. The GTS I have now barely gets to 70psi once everything is heated up. This worries me a little, for I thought that above 6krpm the oil pressure was to definitely be above 70psi. I wonder if oil pressures were higher on my spider due to the Challenge grill it had installed?

Anyway, your help on avg oil temps and oil pressures would be much appreciated.

Thanks,

Nick

 

The oil temp sounds high for not being on a track.

 

Dang! I was afraid to hear that. What could be the cause of high temps without tracking? Oil change needed, possibly? I've not changed any fluids since trucking this car from the buyer. Could the oil be too thin? Perhaps also the reason for the low oil pressures at high rpm?

Nick

 

Update:

I think my high oil temps and pressures no higher than 70psi are due to very thin (worn) oil. I bought this car from someone on the west coast and don't know when the oil was last changed nor what type was used. When I check the level after driving, the oil drips off the stick like water.... not what I'm used to.

I'm changing the oil next week with Redline 5w40 and the gearbox fluid with Redline 75w90ns.

Hopefully that makes the difference.

--Nick

 

Agreed, the oil temps sound high for not being on a track.

What could cause this? The first place I would look is at the oil to air intercooler--get your head in there and see how much road detris has lodged itself in the radiator. Another way for this to happen is for the gauge simply to be sending the wrong temp!

In most cases, thinner oil runs cooler than thicker oil, because it gets pumped through faster. This logic fails when the oil become so thin that wear accelerates and heat goes through the roof. Thicker oil can run hotter (from heat picked up through the pump pressure) but this would show up on the gauge.

Oil pressure reading low is a bit worrysome, also. THis can be caused by a clogged oil filter, thin oil, or excessive clearances.

So the first step along the "let's sort this out" is to change the oil and filter to a brand that you like (hint RedLine 5W-40, Badlwin) and see what the gauges read. Might want to drop a bottle of RedLine water wetter in the coolant, aslo.

 

Perhaps "I'm" reading the gauge wrong? In the posts above, how are you getting such granular readings on your oil temp? If I'm calculating the marks correctly, I have 100, 127.5, 155, 182.5, 210, 237.5, 265, etc. When I drove today, my temps are a steady 237.5. When I begin to drive hard they eventually reach 265. Also, this oil cooler is on the right side, correct? And where (if you know off hand) is the oil temp sensor? Is it on the oil tank? I saw a post referencing a similar oil temp reading error on 348s where they run a ground strap from the tank to the engine. Do you know if this remedy will help to test the oil temp sensor for the f355 as well?

When I cranked up this morning, pressure only reached 70psi. If I revved the car to 4krpm and oil temps below 210, I actually saw pressures higher than 70psi. Once again I'm hoping this is due to the water-like dripping oil.

Redline 5w40 is what I've ordered. Also ordered Redline 75w90ns for the gearbox.

The car runs so, so well. No power issues that I can tell when compared to the 98 F355 F1 Spider that I had. I hope I haven't made a mistake in trading the F1 pump overheating problems with my spider for something more major with this manual, 98 GTS. I called and spoke with the shop that did the major service on this car (Fusion Motorsports in California) a little over 6 months ago and they assured me that the car was in very good working condition. I even have a copy of the itemized receipt for everything done/tested.

--Nick

 

Update:

I inspected the oil radiator and it doesn't seem clogged. The coolant radiator in front of it of course seems to have a little trash in it, but nothing IMO that should cause an issue, after all my water temps run according to what I'm used to seeing.

I visited the Ricambi site to find the placements of the pressure and temperature sensors. I may go as far as replacing the two sensors along with my oil change. In looking up the sensor placements, I noticed that the oil tank has a thermostat in it that seems to allow oil to or not to flow to the radiator. Could this be faulty? Is it as prone to failure as the coolant thermostat is... perhaps opening late?

--Nick

 

Update:

Everything is PERFECT!!! Today it's 60df outside. Driving the car to my friend's shop to do the service, cruising at 80mph, oil pressure was a tad below 70psi and the oil temp was 237df. We changed the oil with Redline 5w40 and the gearbox fluid with 70w90ns.

On the way back home, the outside temperature is still 60df, oil pressures FINALLY reached 88psi and above when revving beyond 6krpm (could barely get 70psi before), and the oil temperature never reached 210df (more like 183df).

When unplugging the oil tank, the oil literally dumped like water!! it was SO thin! I know this affects oil pressures tremendously. As for the high oil temps with the old oil, is it possible that the oil was so thin that it flowed too quickly through the oil radiator, thus not having enough time to cool down??

--Nick

 

Perhaps that makes more since. But as you said, nice to know that fresh oil makes the difference in both oil pressures and temps.

--Nick

 

I had my 355 fans rewired by an Independent Ferrari mechanic. I have a 1995 which uses the 2.7 motronic. The fans heavily tax the OEM fuse panel (example-when fans turn on lights in car dim). So he pulled both of my fans off of the fuse panel and fabricated a seperate fuse and relay. He recommended one fan temp switch to turn both fans on simultaniously. This setup has worked great! I have never overheated my coolant or oil even on the hottest of days in Southern California (115+). My car is a daily driver for both pleasure and canyon driving, I have put 30k miles on my car in 4 years.

 

I had the same problem for a long period of time. After two authorized services rejecting that there was a problem, a specialized service solved it on the spot.. The thermostats sometimes get stuck around 100 Celsius in F355's he said, doesn't let the oil temp drop below that. A new thermostat and never had the problem again...

 

Yes. With the big, bright 36mm bolt on top. Easy, easy replacement. Remove the bolt and all you have is the washer, a spring, and the thermostat itself. You'll need some long needle nosed pliers to reach into the housing and extract the thermostat. No need to unbolt the thermostat housing from the side of the oil tank.

--nick

 

OK. Help me with this scenario. I really think my car is OK, but want to be certain.

The last 3 days I've driven my f355 GTS in 106df + weather. Yesterday it was 110df outside and I drove 248 miles on the highway, AC running, and water temp was 190df and oil temp was around 217df. Does this seem OK?

Today, it was 106df outside and I drove around in the city, AC on, and water temp reaching around 207df when at a stop and oil temp around 217df. If I turn off the AC, water temp never rises above 190df.

Does all of this seem reasonable given the outside weather temps?

 

Yep, completely reasonable.

 

Relief!! Thanks for your response. I'm no longer worried about oil and water temps.

Now... I have to replace the stock headers at 34,000 miles they finally went. I'm sure the 106+ temps and the 600+ miles I drove it this weekend (with AC on) helped them go KaBlewy!!

She sure ran great, though. I'm not surprised that this past Sunday, at 105df outside, 70mph and AC running, water temp was 190df and oil temp was approximately 217df. Then, at 90+ mph, water temp was around 172df and oil temp was around 203df. She loves to go!

Thanks again!