Nissan 370Z Forum - Oil Temp Survey

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- - Oil Temp Survey (http://www.the370z.com/nissan-370z-general-discussions/3901-oil-temp-survey.html)

Quote:

Originally Posted by FuszNissan (Post 465222)

You should be running 245 under spirited driving. Tracking you will need an oil cooler.

So then I guess I would need to find out at what temp the type of oil I use starts to break down and lubricate as well.

Quote:

Originally Posted by Zsteve (Post 465227)

So then I guess I would need to find out at what temp the type of oil I use starts to break down and lubricate as well.

While each brand of oil should show some differences in exact temps, but from a couple quick searches, most conventional oils (which I assume includes Nissan Ester) starts to break down around 250°F and most synthetics appear to be rated up to around 290-300°F.

But what complicates things is that article explaining that the problem for this car isn't that the oil gets so hot that it starts to break down; the problem (according to the author) is that in an effort to be more 'green', Nissan changed the type of metal they use in their bearings, and the new metal is less durable under high heat. The claim is that even if your oil is okay at, say, 280 degrees, the bearings aren't -- they'll start to degrade. You guys know which article I'm referring to? The one by Mike Kojima?

Quote:

Originally Posted by semtex (Post 465258)

Well thats F'd up.

I hope they are not using those clay bearings from the clay model they have sitting around.

Quote:

Originally Posted by Zsteve (Post 465267)

Well thats F'd up.

It's why I installed an oil cooler. I'll tell you guys right now that I never saw temps above 250 prior to installing the cooler. But the claim made in that article had me paranoid enough that I figured better safe than sorry. And on the cooler went.

I never saw temps above 230 with out a cooler, and with one , I have seen temps above 215.

I won't link to the article itself because it's on a competing blog and it's against the rules, but I did just go find it and I'll quote the relevant passages here for you guys to read.

Quote:

To understand limp mode we must understand what it’s protecting in the engine. The most oil temperature susceptible parts are the engines crank and rod bearings. The engines bearings are made of soft metals, such as aluminum, tin and zinc with other trace alloying agents such as indium which refines the metals grain for better mechanical properties. The reason why soft metals are used is that they offer good embedability. If hard contaminates are present in the engines oil such as casting sand, metallic particles, hard carbon bits and dirt, a soft bearing surface will allow the particles to become embedded into the surface of the bearing where the damage to the bearing and crankshaft can be limited. The contaminating particle will be soaked up by the soft bearing instead of being ground into the hard steel journal surface of the crank with damaging effect.

Soft metals can be used as engine bearings because under normal conditions, the crankshafts journals never touch the bearings surface. Since the liquid oil layer is not compressible, the crank rides on a pressurized hydrodynamic film of oil a few thousands of an inch thick that is maintained on the bearings surface by the engines oil pump. The oil pump must maintain pressure (this varies for as low as 5 psi at hot idle to more than 60 psi at higher rpm) and continually replenish the oil because the oil leaks out at the edges of the bearing and is flung out by the centrifugal pumping action of the rotating rod journals. This circulation is necessary because the shearing action of the oil in the boundary layer between the rotating crank journal and the static bearing surface creates heat and this heat must be dissipated. Most of the heat is removed by the oil as it passes though the interface between the bearing and crank.

The bearings, although soft still have to bear a heavy load because the incompressible liquid oil film transfers the forces acting upon the engines reciprocating parts to the bearings, thus the bearings have to withstand thousands of pounds of force even though direct contact does not happen. The best engine bearing have high embedability with a high load bearing capacity.

Usually everything works fine until a couple of things happen. In the case of modern late model engines, the green movement is to blame for part of the problem. In the last few years, Nissan has worked hard to make their cars green and more recyclable. In an engine traditionally one of the most toxic areas was the bearings. A few years ago, many Nissan bearings were made of trimetal construction using layers of lead, zinc and tin alloys of different percentages. This tri metal construction has been a mainstay of heavy duty bearing construction and composition for decades. The old Nissan bearings were very strong, heat resistant and durable. It’s a little known secret that old L-Series Nissan bearings are so strong and durable that many race engine builders use them, adapting them to other engines. The Infiniti IRL engine used in Indy cars used off the shelf L-Series bearings for this reason.

Understand that I'm not necessarily vouching for the accuracy of this information. I'm just sharing it with you guys in case you haven't read it before.

Oops. I missed a couple of additional paragraphs.

Quote:

Sometime in the last few years, in an effort to be greener, Nissan discontinued the use of lead in all engine bearings. We know of this through discussions of sources deep within Nissan which will have to remain unnamed. At this time the engineers at Nissan noticed that warranty claims for bearing failure in the RB26 GT-R engine, another Nissan engine noted for running high oil temps, spiked. Nissan launched an intensive study on the reasons of this bearing failure and discovered that the new environmentally friendly bearings started to loose their load bearing capacity at temperatures as low as 260 degrees. Although there was plenty of reserve strength for normal passenger cars, the turbo high output RB motor pushed many sets of bearings to the failure point. Although you think of lead as a very soft metal with a low melting point, it was still a major contributor to the bearings mechanical properties and resistance to heat.

So as the oil temperatures climb, the bearings soften and loose their load bearing capacity, if the temperature climbs past 300 degrees and the engine is being pushed hard the bearing material can start to flake and spall. This disrupts the hydrodynamic film allowing metal to metal contact, resulting in catastrophic failure of the bearings, the crank, rods and even the entire engine often within seconds. Oil also begins to deteriorate quickly at temperatures above 260 degrees. It starts to oxidize and thicken, loosing its lubricity while forming sludge and varnish. This further compounds the problem, generating more drag and heat in the bearing/crank interface area.

I agree with Semtex. I read that article awhile back and it really got me thinking about the oil temperatures in my car. To be honest I never see my oil temperature go above 220-230(but I haven't driven it hard in hotter weather yet). But, if I see temperatures substantially higher, but still not in limp mode. I may consider an oil cooler without being on the track just for the sake of ease of mind.

The biggest thing that makes no sense to me is. I'd say a VAST majority of members on this forum mod their cars. So why complain about an oil temperature problem with this car if an oil cooler is one of the cheapest mods that can be done to the car? Stop complaining and fix the problem. I'm sure the 350z had this same problem. But without an oil temperature gauge or limp mode ignorance is bliss.

Quote:

Originally Posted by Nick911sc (Post 465304)

the kits are not exactly cheap now. unless you do the DIY kit they are about $400+

Quote:

Originally Posted by Zsteve (Post 465307)

the kits are not exactly cheap now. unless you do the DIY kit they are about $400+

I don't know about you, but after spending $30K on a car spending >500 on an oil cooler seems like a pretty cheap mod. I plan on my car keeping value rather then imploding over that fraction of money. Especially when Exhaust systems are 3-5 times the price(some a lot more)

$400.00 - Oil Cooler
$10,000.00 Engine

Quote:

Originally Posted by FuszNissan (Post 465327)

$400.00 - Oil Cooler
$10,000.00 Engine

Exactly

I think one of the issues with an oil cooler is that Nissan doesn't like us installing them. While I mod my exhaust and cats, Nissan shouldn't have any issues with something happening to my engine. If I install an oil cooler, I'm not sure of the results.

Right, but that brings you back to square one. If you're afraid to put the oil cooler in your car then don't drive it until it overheats. More or less what Nissan has said to its drivers, on the street no cooler, on the track cooler.