A Swiss dudes question

[Raphi]

Hy guys

I drive an R34 GTT actual i use Castrol 10w60. I hear its better to drive with 10w40 like motuls turbolight. I have no oilcooler installed engine is stock with nistune 340ps. Who drives 10w40 from motul with no oilcooler and how good is it, like oil pressure stability oil temp etc.

Thanks  greets from Switzerland

[robbo_rb180]

I use to use the motul 10-40 with no problems. Oil weight should reflect the local environment the car is driven in. 25-38C and 60-99% humidity where I lived when using it.

[niZmO_Man]

10W-40 is fine. If you're on the track and regularly see oil temps going >120 degC, then put an oil cooler in.

[Duncan]

w40 is fine for street use unless the rings are worn then you might want w50.

I guess you already know this, but if it goes below 0 a bit you probably want 0w40 or 5w40 in cold months

[Raphi]

I drive the car only in spring or summer never at winter. I drive normali in the city or on landroads and  mountain and  at this point i push it really hard.

With the 10w60 i got in the summer over 100 degres.

I think the piston rings are good  compressiontest is between 11 and 12 bar. 

Oilpressure with the 10w60 at 90 degres is 2.2 bar at idle speed 1000rpm

So that sems to be ok too.

 

[Raphi]

What for outside temps in your area?

Here it is on summer max 38 degres.

[GTSBoy]

46 minutes ago, Raphi said:

Here it is on summer max 38 degres.

In southern Australia we get weeks at a time >40°C.

[Raphi]

And no problems with 10w40 no oilcooler?

Sporty driving oil temps been ok?

[GTSBoy]

No oil cooler in my car. Oil peaks at around 110°C on the hottest days. Just don't flog the f**k out of it if it's really hot.

[Robzilla32]

Hmmm....oil cooler made a big difference in my street R32 GT-R (Melbourne).

[Raphi]

With the castrol 10w60 supercar the temp gets under full load and  hard drive up to 110 degres. How it looks with the 10w40 i read that the motul turbolight is good for the rb engines. But only for normal drive? And whats with the hths in the oil? 10w60 is 5.8mPa and the 10w40 only on 3.7mPa so is that good? I asked this question because i have  a stock engine but 340hp with the nistune and run 0.9 bar if that helps.

[Duncan]

honestly mate, the car is making pretty basic power levels and you aren't racing it. Modern synthetic (or even semi-synth) oils are excellent compared to the olden days for everything up to short sprint/race use. So chuck in any 10w40 or 5w40 synth you are happy with and save a fortune.

Re temps, personally I'd be looking to keep it under 100, 110 and higher isn't a disaster but it does get hard on everything. Since you say you only drive in summer just add a medium sized oil cooler in good airflow and you should never have to think about it again. Plus, adding an oil cooler is cheaper than putting race oil in every 5000klm

[Raphi]

I have a oil cooler from d1spec  9 or 12 row but not installed because i heard that the oil pressure drops down.

[BK]

Only if your cooler sucks.

A good oil cooler drops temps massively. I run the Trust coolers with 70deg C thermostats, so they don't pass below 70. The 32 has a 13 row and the 33 a 10 row.

Castrol edge 10w60 is good stuff. I use it on 2 of the GTRs, but we also have 45deg C summers. On the big HP RB26s or heavily competition the weights favoured by the big workshops seem to be the 10w60 or 15w50 depending on climate and/or bearing clearances.

With your power level and being a street only car the 10w60 is probably overkill, but it won't hurt it. 10w40 is the generally accepted standard weight for an RB26.

[Raphi]

I have checked it its a 12 row oilcooler.

Is it better 10w40 with oilcooler or 10w60 with oilcooler?

[BK]

What does oil weight have to do with oil temps with a cooler ? It's not like it runs hotter with one or the other.

[Kinkstaah]

Unless you know what the temperature actually is (with a sensor) then you don't really know.

A 10-60 is thicker than a 10-40 at 100C. So it won't change the temp, but it will change the viscosity, so if you're targeting a specific viscosity it could sort of matter.

[BK]

Yes absolutely, which is more of a big end and mains bearing clearance issue regarding viscosity when an engine is really being pushed. Large clearances will require a thicker oil, small clearances lighter oil.

We are talking about a mostly standard engine here so a 10w40 will be more than adequate cooler or no cooler. If he drops in 10w60 still won't hurt it, oil pressure will definitely be more which ain't a bad thing - cooler or no cooler.

[Kinkstaah]

My only fear is that if the engine is REALLY being pushed, as in 130-150+C oil temps, it may be better off having 10-60 in there than 10-40.

There is sorta some logic in going with a thicker oil if you do know it's gonna get hot. That said, there's not a lot of in between where someone will take that as an option before they actually get an oil cooler and get oil temps under control. You should find that with enough cooling it'll be hard to really get up into the 130-150C range anymore, and thus the oil choice tends to be 10-40 or 50 if you really want to go ham/rebuilt engine with more clearances.

Realistically though, still don't think there's been a engine failure on this forum that someone can actually claim was bad oil/wrong oil, at least not in the realm of "10-40 or 10-60"?

 

[GTSBoy]

I think it is important for people to realise something. The difference in viscosity between a 40 oil and a 60 oil, at the temperatures we're talking about (100+°C) is precious bloody little. At 100°C a 60 grade engine oil is sitting at ~20 cSt. The 40 is at about 15 cSt. The gap narrows as they get hotter. At 120+°C there'd only be a couple of cSt in it.

Take a look at the right hand end of this chart to see how all these oil grades collapse towards the same viscosity at the higher temperatures.

 

All this does is tell you that it is VITALLY important to control oil temperature. Selecting a 60 over a 40 is not the correct solution. It's not even a good idea, as it will lead to a placebo effect making you think you're better protected, when, really, not so much.