Oil Temp ? For AEHass

[Bob25thTA]

New to this forum and I enjoy all the opinions.

Dr. Hass, I enjoyed your Oil 101 etc. articles and have a few questions about Oil temps. I have an 03 Corvette which runs normally at about 205 F, Mobil1 0w30 and does not have an oil cooler. I track the car 3-4 times a year and see temps in the 290 F range. I have purchased an Air/Oil cooler without a thermostat to try to keep the track temperatures down. What kind of street temperatures would be considered acceptable?

 

[Gary Allan]

Just giving this a bump since the post will most likely get burried if the good doctor doesn't check in soon enough.

In my opinion, the temp won't be as important as how long it's allowed to remain at peak normalized temp. The leveling off of the oil temp, at whatever temp that may be, marks full thermal saturation of the engine. There's no requirement that you reach 200F ..180F or 160F. They will all liberate moisture and volatiles. It just takes longer at lower temps. Naturally your visc will also be altered to the heavy side.

Your 205F is a good temp. You may not see all that much of a change in normalized temp. There's more then enough excess btu's that the oil can soak up that normally goes to the cooling jacket(s). It may take a few more miles to reach that temp

This installation should unload your cooling system to a decent degree if it's getting peaked during track conditions.

This would be my preferred modality for handling oil temps, but you probably don't have the room:

 

[Bob25thTA]

Thanks for the Bump. I was concerned more with the cSt scenario. If 30 weight synthetic oil is 10cSt @ 212 what is it at 180F or 160F? Thicker, less flow, should 20W be used with the cooler install to get the flow back up?

 

[Toy4x4runner]

My 89 corvette had a Oil pressure and Temp gauge. digital too!! Loved it. anyway... I'd say drive the car around town for a while w/out the cooler and eye your oil temps. Let's say for example they're in the 228F (mine always were) ball park for average driving around town/highway. You put the cooler on and then drive the same and if temps are in the 180, 190 area... it's probly to cold. I'd say try to keep the normal driving oil temps as a bench mark for when you run the cooler. that should give you a good idea of what's going on.

 

[Toy4x4runner]

on my 4runner v6 3vz it has a oil cooler that's tied into the water system. Helps keep oil temps where they should be. those types are the best I think.

 

[Gary Allan]

Quote:

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Thanks for the Bump. I was concerned more with the cSt scenario. If 30 weight synthetic oil is 10cSt @ 212 what is it at 180F or 160F? Thicker, less flow, should 20W be used with the cooler install to get the flow back up?

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I'm assuming regular M1 0w-30

@ 212 11CST
@ 180 16.6 CST
@ 160 22.2 CST

while M1 5w-20 will look like this

@ 212F 8.8 CST
@ 180F 12.8 CST
@ 160F 16.8 CST

You will get no less flow unless your pump is in relief. You'll just spend a little more fractional hp pumping it. I wouldn't sweat that too much. If someone has a 10 miles commute, in a non-exchanged engined vehicle, they probably never break 180F in oil temp.

Engines that have the coolantil coolers have the oil warm up faster then the rad type. They also always tend to gravitate to 200F+/- in oil temp most of the time.

 

[427Z06]

Lot of good advice so far, but I'll add a few other things to think about.

As far as a minimum oil temperature when you car is at operating temperature under normal driving conditions, consider the setting of most oil thermostats is at 176°F(80°C). I would use that as a lower boundary. But another point to consider is how long it takes to reach that lower boundary. In the summer, it may take 10 min or 10 miles to reach 205°F without the cooler, or 10 min or 10 miles to reach 176°F with the cooler, and that's probably acceptable. But things may change significantly in the winter time. Cruising down the highway on a cool crisp winter morning, it may take 30 min or 30 miles to reach 176°F with the cooler, if it ever does. I would consider this borderline acceptable unless 95% of your trips were at least this far.

 

[LargeCarManX2]

Bob said he see's temps at the track of 290 F when he races. Bob is that oil or coolant or both? 290 is smoking hot. If the coolant is running in the 180 to 200 range...a oil cooler routed thru the coolant is in order. Wow..290

 

[sidney004]

The 290F is oil temp. I track a 94 LT1 and on its last outing, the oil temp was 295F. The normal range for track driven LS1 and LS6's that are track driven are 290-310F. Interestingly, my oil temps DROPPED when I switched from RL 10w30 to RL 10w-40 from 305F to 295F under similar conditions, don't ask me why. There was speculation on this board or the Corvette forum that a thicker viscosity reduced ring flutter, which reduced blowby, which decreased oil temps, who knows but the oil temps did in fact drop with the increased viscosity. By the way, the UOA's on corvettes run in this type of application are not pretty, at least not mine.

 

[Gary Allan]

Sidney, how does your coolant run under these same conditions?

 

[TurboJim]

Is there a reason GM is building Corvette's with out some sort of oil cooler? Would a coolant / oil unit simply not be able to keep up?

 

[XS650]

Quote:

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Is there a reason GM is building Corvette's with out some sort of oil cooler? Would a coolant / oil unit simply not be able to keep up?

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$$ They build to a price. The Z-51 option does include a cooler.

 

[427Z06]

Quote:

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There was speculation on this board or the Corvette forum that a thicker viscosity reduced ring flutter, which reduced blowby, which decreased oil temps, who knows but the oil temps did in fact drop with the increased viscosity.

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This is a known issue among GM engineering types and was fixed on the LT4. Funny is the fact that the first LS-1s had a similar issue until they changed the ring design on those too.

 

[enjoythemusic]

Quote:

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The 290F is oil temp. I track a 94 LT1 and on its last outing, the oil temp was 295F. The normal range for track driven LS1 and LS6's that are track driven are 290-310F.

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Wow that is high, but then again if they did indeed design that in from the factory. Track the Ferrari 308 a lot and before mods (two years ago) my coolant was at 125C and oil at 140C. Felt this was way too high and went with a more effective than stock radiator. Now my coolant temps are around 95C and oil stays solid at 110C. Note that the Ferrari 308 does have an oil cooler with large (10AN connectors) lines and has good air cooling/ducting. Your 290F makes me concerned as the oil viscosity must really thin down and makes me wonder how low your oil pressure goes due to this fact. If it was me, i'd install an oil cooler that received good air flow to get temps down to 120C or lower.

Quote:

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By the way, the UOA's on corvettes run in this type of application are not pretty, at least not mine.

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This speaks volumes. Again, if it were me i'd run lines to an oil cooler that received good air flow. Excessive engine heat in general can cause various other problems...

Try online stores such as Pegasus Racing or HRP World. Hope this helps.

FYI: last week was at a 7 hour open track event, not the usual full day = 90 minutes of tarmac use. Must have been on track for 4 hours (ambient temps 70F, mixed sun/clouds, tarmac at 90F) and the 308 never got above 90C coolant and 110C oil. Call it a durability test for the car as we did many mods to her plus i was using AutoRX for the first time to flush her even though we looked up the oil galley after removing the entire pan and things were clean. We are prepping for a Supercharger and wanted to 'torture test' the car because rebuilding the engine this winter makes more sense than rebuilding in a rush mid-2007 season.

Again, my concern for your Vette is you may be shortening her life due to excessive heat and the UOA seem to echo this acccording to you. An oil cooler is your friend

 

[sidney004]

My coolant temps run about 230 when the oil temp is 290+, I run a 25% concentration green antifreeze + 1 bottle RL water wetter. I can't comment on the effectiveness of Water Wetter, but I like the color. The oil cooler is an option, but right now I would rather spend my money on R compound tires and racing brake pads.

 

[enjoythemusic]

Quote:

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My coolant temps run about 230 when the oil temp is 290+, I run a 25% concentration green antifreeze + 1 bottle RL water wetter. I can't comment on the effectiveness of Water Wetter, but I like the color.

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Tried water wetter and found it ok, but did not make much of a difference. Think it is really for those who use 100% water yet still need a lubricant for the water pump. It claims to also help cooling.... Might flirt with Evans stuff as i have it here, though so far the 25% green with water seems fine.

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The oil cooler is an option, but right now I would rather spend my money on R compound tires and racing brake pads.

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Agreed Hoosiers or the like are fun and brake pads being a MUST of course. Always keep three sets of pads on hand and two sets of extra rotors+hardware for all corners.

Look, oil coolers are only about $125 (versus $1k for good r-compound rubber) and guess about another $35 in hardware/hoses. It is your engine, do as you desire. If it was me, i'd get temps to a more reasonable level but then again the guy typing this errors on the side of caution. Rebuilding the engine here reaches $10k+. Your call.

 

[sidney004]

It is a tight fit on these model year corvettes. To do it right with an Accusump to prevent oil starvation, my mechanic quoted me a tidy sum. An oil cooler should drop working temps by 40 F but I believe that a quality ester like Redline is capable of providing adequate protection even at these elevated temps. By the way, I am getting R compound scrubs(V710's and Hoosier GAC's) at $75 a piece, that is probably not an an option on the Ferrari's size(what size do you use?)

 

[AEHaas]

All of the points made are valid. Red Line oils can take those temperatures but 290 F is up there. A cooler would be good in your racing application but you may run too cool around town. It will also take too long for the oil to warm up around town. An on - off switch so that the cooler only works on the track or a thermostat is in order.

We need a graph of oil temperatures vs pressures both at normal around town driving and for track driving to better recommend an oil weight.

If things stay as they are without a cooler I would recommend the RL 40 wt. oil having no other information to go on.

aehaas

 

[Bob25thTA]

I guess my original thought was Oil weight should be chosen by normal operating temperature not pressure. If we know our normal around town oil temperature Corvette 205F and Ferrari 180F. Wouldn't you choose 30W for the 205F engine and 20W for the 180F engine, so that you get and approximate 10cSt? And then use a cooler to try to maintain those temperatures.

 

[Bob25thTA]

Mocal has a couple of thermostats I can use one is set at 180F and the other is 200F. What are your opinions on which thermostat I should use? I am leaning toward the 200F, because that is my engines normal operating oil temp.