Hot Climate Engine Oil?
05-28-2013, 09:50 PM
#16
Is it not a net positive for the oil to be cooled by the water, as there are fans and many controls on the coolant temperature, and when you have an external oil cooler you have a radiator with no fan and only ambient as the cooling medium?
05-28-2013, 10:07 PM
#17
Electron Wrangler
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I think both is a good compromise - first Air/Oil in ext cooler to take care of cooling when running and then the Oil/water in the side tank to take care of the no airflow situations. Although there is a heavier loading then - you presumably are just in a dynamic cooldown situation as long as you stay ~ idled so you just need the inertial cooling buffer capacity to tide you over - not long term heavy duty oil/water cooling. The oil/water also avoids overcooling the oil (keeps it at nice comfy temps).
Better oil & dual coolers has made a big difference to my car in 110F - & occasional ~120F days (very low humidty too - very nasty conditions).
I'm using AMSoil 20W50 ZROD, huge improvement over Mobil1 15W50. New rod bearings also helped marginally with low hot pressures.
Alan
Better oil & dual coolers has made a big difference to my car in 110F - & occasional ~120F days (very low humidty too - very nasty conditions).
I'm using AMSoil 20W50 ZROD, huge improvement over Mobil1 15W50. New rod bearings also helped marginally with low hot pressures.
Alan
05-28-2013, 10:26 PM
#18
I found it interesting that my GT (89) ran a needle width or two (take that for what its worth) higher than the 90GT and other 928's that had air fed oil coolers on the Wichita OCIC trip last summer. It was hot and A/C was on.. high speeds etc....
(the 89GT has the cooler in the rad side tank..the 90 and up 928's have the air cooled oil cooler)...
(the 89GT has the cooler in the rad side tank..the 90 and up 928's have the air cooled oil cooler)...
I'm certainly "estimating" at what I think oil pan temperatures should be. I figure that the oil is going to leave the pan, get pumped through the oil cooler, and then to the bearings. I figure that at 240 or 250 degrees, the oil can still be cooled down by the water in the radiator....perhaps not, by the looks of your two gauges, Tony.
Very interesting.
Makes one wonder if the water temperature is high because of the oil being cooled down by the water. Porsche did "justify" that they removed the oil cooler from the radiators in the later vehicles because the radiator was not able to deal with the thermal load from cooling the oil, as the power output went up.
Do you know if your '87 has the piston sprayers or not? The 968 engines seem to universally have very hot oil/low oil pressure and some people suggest that this is the result of the sprayers.
Very interesting.
Makes one wonder if the water temperature is high because of the oil being cooled down by the water. Porsche did "justify" that they removed the oil cooler from the radiators in the later vehicles because the radiator was not able to deal with the thermal load from cooling the oil, as the power output went up.
Do you know if your '87 has the piston sprayers or not? The 968 engines seem to universally have very hot oil/low oil pressure and some people suggest that this is the result of the sprayers.
05-29-2013, 08:40 AM
#19
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This is the type of forum that is particularly helpful to a fairly new 928 owner like me. My original question was answered X 10.
What I have gathered from this is that an additional Engine oil cooler is a necessity for running a Boosted car in Hot temp's. Running a engine oil such as Torco-1 20/50 or others with high Z and P or even a 50 Weight should offer the cooling properties necessary for lubrication and cooling to withstand the heat of a 95 Degree F Nashville summer afternoon. And... that an engine oil temp gauge should be used to monitor engine oil temperatures in order to make changes in oil's if needed.
I remain grateful for all the assistance.
What I have gathered from this is that an additional Engine oil cooler is a necessity for running a Boosted car in Hot temp's. Running a engine oil such as Torco-1 20/50 or others with high Z and P or even a 50 Weight should offer the cooling properties necessary for lubrication and cooling to withstand the heat of a 95 Degree F Nashville summer afternoon. And... that an engine oil temp gauge should be used to monitor engine oil temperatures in order to make changes in oil's if needed.
I remain grateful for all the assistance.
05-29-2013, 12:01 PM
#20
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From the industrial side, thicker oil does a poorer job of transferring heat. That works both ways, since it doesn't pick up as much and similarly doesn't shed as much. It usually isn't that balanced since it tends to be thinner on the heat-gathering side of the loop, and thickens as it cools again on the heat-shedding side. Same deal in the car, but recognized differently. As Greg points out, there are critical do-not-exceed numbers beyond which the oil starts to break down, so your choices are narrowed down to running a thicker oil so it doesn't gather so much heat (and risk lubrication failure), or figuring out another way to shed some of the engine heat, like bigger/cleaner radiator, moving trans cooler load from the radiator, removing oil cooler load from the radiator, improving airflow, improving coolant flow, eliminating AC load in front of the radiator.
05-29-2013, 01:30 PM
#22
Nordschleife Master
Writing of Rube Goldberg machines, I did dream up a street dry sump system that would use both tank end coolers and an external oil cooler in a 5-speed car.
The scavenge pressure line would run thru upstream side end tank before oil making it to the tank, no thermostat in line. Then on the pressure feed side, there would be a thermostat controlled cooling loop that would go thru both the external oil cooler and the end tank cooler.
The benefits of the system (on paper, in practice this is too complicated to do any good) would be the following: On startup, coolant heats up quicker than oil. Running the scavenge pressure line thru the radiator end tank helps bringing up the oil temps quicker when the engine is cold and down when the engine is hot. The thermostat controlled cooling loop on the pressure side would go thru both one of the end tanks and and an external cooler, the end tank part helping cooling in traffic when there's no air flow except the fan.
The above would be a definite violation of the KISS principle.
I do however like your idea of running both the end tank and external coolers in series, not too complicated.
The scavenge pressure line would run thru upstream side end tank before oil making it to the tank, no thermostat in line. Then on the pressure feed side, there would be a thermostat controlled cooling loop that would go thru both the external oil cooler and the end tank cooler.
The benefits of the system (on paper, in practice this is too complicated to do any good) would be the following: On startup, coolant heats up quicker than oil. Running the scavenge pressure line thru the radiator end tank helps bringing up the oil temps quicker when the engine is cold and down when the engine is hot. The thermostat controlled cooling loop on the pressure side would go thru both one of the end tanks and and an external cooler, the end tank part helping cooling in traffic when there's no air flow except the fan.
The above would be a definite violation of the KISS principle.
I do however like your idea of running both the end tank and external coolers in series, not too complicated.
I think both is a good compromise - first Air/Oil in ext cooler to take care of cooling when running and then the Oil/water in the side tank to take care of the no airflow situations. Although there is a heavier loading then - you presumably are just in a dynamic cooldown situation as long as you stay ~ idled so you just need the inertial cooling buffer capacity to tide you over - not long term heavy duty oil/water cooling. The oil/water also avoids overcooling the oil (keeps it at nice comfy temps). Better oil & dual coolers has made a big difference to my car in 110F - & occasional ~120F days (very low humidty too - very nasty conditions).
05-29-2013, 01:54 PM
#23
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I do however like your idea of running both the end tank and external coolers in series, not too complicated.
For whatever it's worth, here's the (solo) oil cooler in the Zombie. My understanding from Mark is that he had more issues with transmission oil temps (until he ran a big cooler up front) then engine oil temps :
05-29-2013, 02:02 PM
#24
Nordschleife Master
05-29-2013, 02:48 PM
#25
Former Sponsor
Thanks.
Most of the engines that I take apart from the vehicles equipped with the oil cooler below the radiator (1990-1995) have camshafts that are very unhappy....and I concluded that part of this was because the oil simply was too hot to properly lubricate these pieces.
The oil cooler below the radiator has no fan....no when someone is stuck in traffic, there isn't much "oil cooling" going on....and the result is really high oil pan oil temperatures. While the idea of putting a separate oil cooler under the radiator, without a fan, might have worked great in Germany....it seems like an exceptionally poor idea for "traffic", like is found in much of the US.
If you don't think so, ad an oil temperature gauge to your pan and go sit in a traffic jam in Los Angeles (or even worse, in Phoenix or Dallas), in the summer, with the A/C running. 300 degree oil is common.....
I simply "combined" both styles of coolers, with a three hose set-up. Initally did this for my "hot-rod" engines and then started doing this to "street" engines, once I saw how high their oil temperatures were.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
The downside is that one needs to either "add" an oil cooler into the left radiator tank, or needs to install an earlier radiator with double coolers on these '90-95 vehicles....and "core" hose sets (from the '90-'95 vehicles....I re-use the stock hose ends) are tough to find.
Retrofitting the second cooler (in this case adding the cooler under the radiator) into an early car is possible, too.
Most of the engines that I take apart from the vehicles equipped with the oil cooler below the radiator (1990-1995) have camshafts that are very unhappy....and I concluded that part of this was because the oil simply was too hot to properly lubricate these pieces.
The oil cooler below the radiator has no fan....no when someone is stuck in traffic, there isn't much "oil cooling" going on....and the result is really high oil pan oil temperatures. While the idea of putting a separate oil cooler under the radiator, without a fan, might have worked great in Germany....it seems like an exceptionally poor idea for "traffic", like is found in much of the US.
If you don't think so, ad an oil temperature gauge to your pan and go sit in a traffic jam in Los Angeles (or even worse, in Phoenix or Dallas), in the summer, with the A/C running. 300 degree oil is common.....
I simply "combined" both styles of coolers, with a three hose set-up. Initally did this for my "hot-rod" engines and then started doing this to "street" engines, once I saw how high their oil temperatures were.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
The downside is that one needs to either "add" an oil cooler into the left radiator tank, or needs to install an earlier radiator with double coolers on these '90-95 vehicles....and "core" hose sets (from the '90-'95 vehicles....I re-use the stock hose ends) are tough to find.
Retrofitting the second cooler (in this case adding the cooler under the radiator) into an early car is possible, too.
05-29-2013, 03:01 PM
#26
Nordschleife Master
T I simply "combined" both styles of coolers, with a three hose set-up. Initally did this for my "hot-rod" engines and then started doing this to "street" engines, once I saw how high their oil temperatures were.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
That's why my Rube Goldberg dry sump plan had the end tank cooler on the scavenge out line on the way to the tank. Can't think of an analogous arrangement for a wet sump engine,.
05-29-2013, 11:58 PM
#27
Former Sponsor
The coolers are still on the thermostat controlled oil circuit, right? So that system shouldn't see oil flow before the oil temperature is already up, and there's no oil warming benefit. Unless if the thermostat opens partially very early, does it?
That's why my Rube Goldberg dry sump plan had the end tank cooler on the scavenge out line on the way to the tank. Can't think of an analogous arrangement for a wet sump engine,.
That's why my Rube Goldberg dry sump plan had the end tank cooler on the scavenge out line on the way to the tank. Can't think of an analogous arrangement for a wet sump engine,.
Try it, if you live somewhere cold.
05-30-2013, 12:04 AM
#28
Nordschleife Master
Regardless, hooking up the end tank and external cooler in series is a no brainer.
12-23-2013, 09:33 AM
#29
Pro
Thanks.
Most of the engines that I take apart from the vehicles equipped with the oil cooler below the radiator (1990-1995) have camshafts that are very unhappy....and I concluded that part of this was because the oil simply was too hot to properly lubricate these pieces.
The oil cooler below the radiator has no fan....no when someone is stuck in traffic, there isn't much "oil cooling" going on....and the result is really high oil pan oil temperatures. While the idea of putting a separate oil cooler under the radiator, without a fan, might have worked great in Germany....it seems like an exceptionally poor idea for "traffic", like is found in much of the US.
If you don't think so, ad an oil temperature gauge to your pan and go sit in a traffic jam in Los Angeles (or even worse, in Phoenix or Dallas), in the summer, with the A/C running. 300 degree oil is common.....
I simply "combined" both styles of coolers, with a three hose set-up. Initally did this for my "hot-rod" engines and then started doing this to "street" engines, once I saw how high their oil temperatures were.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
The downside is that one needs to either "add" an oil cooler into the left radiator tank, or needs to install an earlier radiator with double coolers on these '90-95 vehicles....and "core" hose sets (from the '90-'95 vehicles....I re-use the stock hose ends) are tough to find.
Retrofitting the second cooler (in this case adding the cooler under the radiator) into an early car is possible, too.
Most of the engines that I take apart from the vehicles equipped with the oil cooler below the radiator (1990-1995) have camshafts that are very unhappy....and I concluded that part of this was because the oil simply was too hot to properly lubricate these pieces.
The oil cooler below the radiator has no fan....no when someone is stuck in traffic, there isn't much "oil cooling" going on....and the result is really high oil pan oil temperatures. While the idea of putting a separate oil cooler under the radiator, without a fan, might have worked great in Germany....it seems like an exceptionally poor idea for "traffic", like is found in much of the US.
If you don't think so, ad an oil temperature gauge to your pan and go sit in a traffic jam in Los Angeles (or even worse, in Phoenix or Dallas), in the summer, with the A/C running. 300 degree oil is common.....
I simply "combined" both styles of coolers, with a three hose set-up. Initally did this for my "hot-rod" engines and then started doing this to "street" engines, once I saw how high their oil temperatures were.
One of the benefits that I didn't initially see, was that the oil running through the radiator actually gets warmed up quicker...so besides cooling the oil better in hot weather, this system also warms the oil up quicker, in cold weather, for these 1990-1995 vehicles.
The downside is that one needs to either "add" an oil cooler into the left radiator tank, or needs to install an earlier radiator with double coolers on these '90-95 vehicles....and "core" hose sets (from the '90-'95 vehicles....I re-use the stock hose ends) are tough to find.
Retrofitting the second cooler (in this case adding the cooler under the radiator) into an early car is possible, too.
Thankyou Greg.
Your post confirmed my thinking.
Ever since buying my '90GT it has annoyed me that it always ran a couple of needle widths hotter than my '89S4, particularly in slow traffic. It was extra heat I could/can feel in the cabin. Did all the usual fan operation and temp checks. No radiators blocked etc. Hmmmm. Winter months came and went and I thought little more about it.
Now driving the car regularly and with the summer temps here on the rise (35C for tomorrow) I noticed the coolant temp at 90C BUT the oil pressure getting as low as 4bar. Errrk.
Can only be one thing: hot oil. Hmmmm. Get under front and hose oil cooler from the rear to dislodge leaves, insects etc.
Then the penny dropped.
Well not so much a penny as an anvil, on my head from a great height (Wyle E. Coyote style): no cooling fans !!! WHAT? !!!
My BMW R1100S sports bike has the identical problem.
Vot iss eet veeth zeezse Germans? Do zey all sink ve all liff on ze autobahn?
Achtung. Got Himmell. Mine got, and all those other german war movie sayings.
Until I can set up a second cooler I'll fit a clutch of industrial-strength computer-style cooling fans across the back of the oil cooler. Same as I did for the R1100S.
Will post results of success or otherwise.
Cheers
UpFixen.
