What is the oil temperature in turbos?

[zoomzoom]

Just got a 2001 Audi S4 biturbo..one for each bank...I am doing auto-rx now and wondering which oil to use after rinse phase...

Does anyone know what are typical oil teperatures ih small high spining(100K rpm) turbos like my car has?

the car is chiped so it puts out about 325HP compared to stock 250HP.

Oils I am considering are GC and M1 5w-40..one has HTHS of 3.5 the other is 4.1 I belive.

thanks for your input!

 

[Bio-T]

I honestly do not know the temp of the oil when in the turbo, but it goes through very fast. The main job of the oil is to lube and cool. I do have a temp probe on the pre-turbo and post-turbo exhaust. Out of the manifold into the turbo, temps of 1250F under load (I try to keep it under that, but do and can exceed this temp) are seen with 19-20 psi boost, and usually 2-300 less out of the turbo in this same scenario. Running down the highway 70-75 mph, unloaded, 5-700F turbo inlet temp. with 3-5 psi boost.

So you can see that oil is extremely important in a turboed engine. Now add a dual turbo, darn double the work the oil has to do. I know my readings are off a PSD, but the temps are what are generally seen. In fact in your engine, you may see much higher.

Just me personally, I would use the Delvac1/Truck/SUV 5W40. It will be around OTC, while GC is limited to your on hand supply for long range use.

[ May 11, 2005, 04:24 PM: Message edited by: 59 Vetteman ]

 

[bigpaulo]

zoomzoom, what happened to the Mazda?

 

[zoomzoom]

quote:

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Originally posted by bigpaulo:
zoomzoom, what happened to the Mazda?

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Mazda is up for sale..If you know anyone that needs good used car let me know

!

It has been great car..bought it new..0 problems!

 

[zoomzoom]

I also wonder how would turbo wear show in UOA?

 

[williar]

The temp in my Audi 2.7t using GC or M1 0w40 usually runs about 225° F, never over 250°.

 

[pscholte]

quote:

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Originally posted by williar:
The temp in my Audi 2.7t using GC or M1 0w40 usually runs about 225° F, never over 250°.

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Same here for my 2.7T, BUT I believe that immediately after the oil departs the turbo shafts it is a good deal higher than that...

 

[Stinky Peterson]

quote:

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Originally posted by zoomzoom:
I also wonder how would turbo wear show in UOA?

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The main thing we watch for is an increase in copper of about 25-75 ppm. When we see this we do a microscope exam to look for particles. Copper is tricky to call because it's commonly involved in chemical reactions so it doesn't always indicate abnormal wear. In my opinion a microscope check is required to correctly diagnose cases of elevated copper. In lieu of a microscope exam the filter should be cut open and inspected for debris. Other indicators include elevated soot, lead, tin, silver, black smoke, and overall poor performance

Here is a report of an engine with a failed turbo.

 

[zoomzoom]

Interesting...
I would expect to see more Pb in that report

 

[1sttruck]

Oil temps while the turbo is running don't seem to be the issue, it's the shutdown after high loads that can be a problem. On my turbo diesel the exhaust gas temperatures can evidently get above 1200 degrees or so with high loads, so the maker recommends that one let it idle for a few minutes before shutting down after towing up hills, at high speeds, etc., as diesels cool quickly at idle.

 

[JHZR2]

Id go with M1 5w-40 Ill bet its a great fit for that engine.

Oil temp in the turbo is a function of flowrate through. The difference in temperature could be a fraction of a degree through the turbo, or it could be many degrees. The bigger issue is coking of oil in the turbo if you shut it down shortly after a hard driving - get a turbo timer if youre going to drive the car hard.

JMH

 

[Quattro Pete]

Check the UOA section for reports of various oils in that 2.7tt engine. GC, M1 0w-40, Amsoil 0w-30, Redline 5w-30 are all performing well in this application. This engine is not as hard on oil as one might suspect, partly due to relatively large oil sump, me thinks.

 

[rjundi]

quote:

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Originally posted by JHZR2:
... The bigger issue is coking of oil in the turbo if you shut it down shortly after a hard driving - get a turbo timer if youre going to drive the car hard.

JMH

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I agree an issue with turbo cars is temperature of oil inside the turbo. However the idea of a turbo timer comes from the days of oil cooled turbo's. Modern turbos are oil and water cooled. Good designs will continute to flow either fluid by pump or even simply by convection (my Subaru WRX does with coolant) to alleviate temperature.

Lastly its so rare to drive a car hard and immediately shut down. You typically at or near idle speed as you roll to a stop, back up or whatever when parking or travelling through a parking lot or neighborhood.

I personally think turbo timers are another gimmick sold to make some money and expensive at that.

 

[zoomzoom]

quote:

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Originally posted by Quattro Pete:
Check the UOA section for reports of various oils in that 2.7tt engine. GC, M1 0w-40, Amsoil 0w-30, Redline 5w-30 are all performing well in this application. This engine is not as hard on oil as one might suspect, partly due to relatively large oil sump, me thinks.

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I know I did look over those UOA-s and what I am wondering about is this:

What is more important for this and for turbo aplications in general HTHS of oil or its "regular" viscosity at operating temperature?

For example Redline 5W-30 has HTHS of 3.8 while Mobile 1 0W-40 has 3.5?

As far as I could tell my oil temp under normal driving on highway is between 200 and 225( closer to 200) and their respective viscosities at 100C are 10.9 cSt for redline and 14.3 cSt for Mobil 1...

Are ester based oils better for turbo in general due to their higher flash point?

 

[bulwnkl]

Although it can be difficult, there are 2 things one ought to do in your ciscumstance. 1, throw away comparisons to temperatures in diesel engines. 2, remember that your turbos are water cooled. Turbines are not hard on the oil itself (very low shear rates), and except for some heat they are really not a factor for oil selection in a modern engine.

Your car should not be boosting (the way a PSD is) during freeway cruising at any legal speed in the USA. The turbines are spinning, of course, but not working.

Heat is also essentially not a factor in a street-driven car with water-cooled turbos. A short cooldown is, IMHO, in order if you're driving very hard and immediately park it, but otherwise just drive like normal. Remeber that each of those turbos is quite small, and their lower mass makes them very easy to cool quickly.

If you're still concerned about heat, run RedLine in either the 10W30 or xW40.

 

[Idrinkmotoroil]

quote:

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Originally posted by bulwnkl:
Although it can be difficult, there are 2 things one ought to do in your ciscumstance. 1, throw away comparisons to temperatures in diesel engines. 2, remember that your turbos are water cooled. Turbines are not hard on the oil itself (very low shear rates), and except for some heat they are really not a factor for oil selection in a modern engine.

Your car should not be boosting (the way a PSD is) during freeway cruising at any legal speed in the USA. The turbines are spinning, of course, but not working.

Heat is also essentially not a factor in a street-driven car with water-cooled turbos. A short cooldown is, IMHO, in order if you're driving very hard and immediately park it, but otherwise just drive like normal. Remeber that each of those turbos is quite small, and their lower mass makes them very easy to cool quickly.

If you're still concerned about heat, run RedLine in either the 10W30 or xW40.

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Darn good advice IMO. I like the Redline 10w-30 for my turbo setup, my oil sump temps are in the 75 degree celcius range during normal driving, no idea what temps get to in other areas of the engine.

 

[zoomzoom]

Has any of you guys tried to run Redline 5W-20 in your turbo cars...It has HTHS of 3.3...

So on paper it should protect well right?

 

[LarryL]

I have a 96 Volvo 850 Turbo and run Red Line 10w-40. This car makes frequent trips to Phoenix from San Diego. In the summer it's a hot run, 85+ mph, 100+ outside temps and straight open roads and some mountains. I tried Mobil 1 0w-40 but had a problem. This car has a switch that blocks use of the A/C if the oil temp gets too high or the pressure drops too low. This happened twice with the M1 and never with the Red Line. I switched right back to Red Line and it never happened again. This car is a black wagon and without A/C on this trip it's like driving in an oven. Running Red Line is a lot cheaper than adding an oil cooler.

 

[AEHaas]

Red Line 5W-20 is going into my new Maybach 57 very shortly. It has twin turbos in the V12 giving me around 650 BHP and 750 torque (Renntech chip-set). My 0-60 sprint when new was 4.8 flat.
A well broken-in loaner with normal chips did the same sprint in 4.95 seconds. I am hoping to get it down to 4.5 or 4.6 after break-in and using thinner (but higher temperature tolerant) oil.

aehaas

 

[Volvohead]

As said, the temps near the bearing will be elevated a little after shutdown, but not extreme as in the old days without water cooling. Leave it run at idle for 30 extra seconds before shut down if you want a little extra piece of mind.

A *little* shearing is not necessarily a bad thing, unless you absolutely need the full rated viscosity.

I'd definitely go with the Delvac 1 year round if it were me in DC. It won't shear down, if that's the big factor. GC by all accounts is great too, but there are posts suggesting that the current production is not the same stuff.

325 . . . guess it's time to tune my R a little.