Oil temp takes a long time to come up - normal?

[dcdoug]

My 427 SO normally runs about 80-90c oil temp, 80-100c water temp, depending on the outside air temp and if I am moving or in traffic. Oil pressure is 50-60 psi typically (will drop into the 45 psi range after quite a bit of driving). I run an oil cooler.

The water temp comes up pretty normally (especially when I leave the fans off at the start), but the oil temp takes a long time and the needle doesn't move off of 60c for about 5 min. Probably takes 15 min to get to 80c (although that was this AM and it was only about 40 degrees out). But regardless it seems to take longer than I would expect.

Is this a symptom of FE engines, or the fact that I have mechanical gauges and they take longer than electric gauges to register change or something else? Or is this just normal for any engine and I have never noticed because there isn't usually an oil temp gauge....

I am sure there is another thread that answers this question, but I couldn't find it so thought I would start a new one.

[Rick Parker]

Pretty normal for all engines Doug. Even in the summer heat, the oiling system and it's limited cooling capability is secondary to that of the normal cooling system. It will be the last to show temprature, and only after the regular cooling system has begun to reach its BTU dispersal capacity.

Edit:
Although it is totally "Foreign" to our cars and their time period, a conventional water radiator with a separate section for the oil to share some of the generated heat VS a separate oil cooler could be utilized with very good results, although a separate inline oil thermostat and air to air cooler seems to be the more popular (original) way of thinking (???)

Until (WE) begin to "Lean" on these cars (with your right foot) and generate horespower/heat, they generally have more than enough cooling capacity and the oil is slow to show any temprature.

[Bob In Ct]

Doug:
Remember, the oil cooler does not have a thermostat. Also keep in mind that most of our cars are running lots of oil (8 to 10 quarts). I have a Windsor with a 9+ quart pan and it seems to take forever, even with the oil cooler covered, to get the oil up to 180 F.

Bob

[kitcarbp]

Doug, I agree with Rick, these temps are to be expected in the ambients you ref.. There is alot to this topic, sorry this is long but thats why many modern engines use oil/water coolers (stacked plate type cooler) between oil filter and engine block), you want the oil to come up to temp fast as possible to limit engine wear (H2O build-up + acids, etc) get good mpg's, and then keep oil temps in the safe zone to extend oil life as long as possible. The mpg example is best served by example of Honda qualifying their modern 3.5L V6 on the EPA cycle using only 5-20W oils to reach their mpg corp. targets. Combined with better oil formulations we get the longer oil drain intervals these days as well. The "old school" air-oil coolers our Cobras run are best used (and was the best solution in the 60's) in racing at max hp conditions to work, if you want to run them for the "look" on the street, some use a cooler by-pass; manual or thermostatic so you can keep oil temps up in the normal range in cold climates. The 176F (80C) you mention as normal temp is a bit low in my opinion, I would want to see oil temp closer to 200F in winter and max of 225F in summer heat at highway rpms. If you run your car in the lower ambients at these lower (160-180F) oil temps you will "increase" engine wear if you dont run your oil in the 200-225F range as an example. But then if you change oil every 500 miles on these hobby cars, this wear can be minimized also. There are so few Cobras that run a ton of miles each year so you could argue its an academic point only. On the carb'd engines we also care about unburnt hydrocarbons (gas) in the oil contributing to cylinder wall wear over time, not a concern on modern EFI motors, another reason you want to keep the oil temps up on old school engines. My build is still too new to know, but if I ever want to add an engine oil cooler, the way I will go is the modern stacked plate water-oil type, they are reliable, cheap and will keep the avg. oil temp range in a more narrow window and I'll never even think about the oil temps, topic closed.

my 2cents

bill

[dcdoug]

OK, thanks. Other than that, my temps seem to be pretty reasonable?

[DAVID GAGNARD]

Originally Posted by dcdoug

OK, thanks. Other than that, my temps seem to be pretty reasonable?

Temps seem fine............. Oil temp usually "follows" the water temp, but anywhere from 5 to 15 minutes behind it, depending on your oil capacity and outside air temp.......


I'm just using an educated guess, not facts, but I would think your water pump will pump quite a few more gallon per hour than your oil pump, thereby taking longer for your oil to be pumped thru the engine and warmed up...

On my racecar with the road race pan/oil cooler/remote big filter and 12 AN lines, it holds a total of 11.5 quarts of oil..... On warm days (say 60 degrees or more) oil temp will come up in 5 to 10 minutes, on days when the temp is in the high 40's or 50's, add at least another 5 minutes........

Also, after a 20 to 30 minute track session, my water temp will be somewhere bewteen 180 and 190, (always) and my oil temp usually around 240, maybe 250, park the car and the oil temp will come down a lot faster than the water temp (mechanical gauges)...........

I have raced some in 40 degree weather and my oil temp would barely reach 180, so I generally put one piece of duct tape across the oil cooler on cold days to get the oil temp in the low 200 degree range.......

David

[Mdman352]

Originally Posted by dcdoug

OK, thanks. Other than that, my temps seem to be pretty reasonable?

Doug,
Yes. I drove yesterday and it may have hit 65 outside. Took quite a while for oil to come up in temperature.
David

[fastd]

How accurate do you think the oil temperature sensor is, especially in cold weather? The reason I ask is that my oil temp characteristics are pretty consistent with what was written above. However, one additional observation: on cool days especially, for example, when my gauge reads 70 degrees and I come to a stop sign, the gauge quickly (within a minute or two) runs up to 80 degrees; if I turn off the car it goes even higher. When I start driving again it will go down to 70 very quickly, on cold days down to 60; all within seconds/minutes. Can the temperature of your entire oil system really change that quickly? Or is it that some parts of your system, or just the air flow on and around the temperature sensor are causing your gauge to move around?

[DAVID GAGNARD]

Originally Posted by fastd

How accurate do you think the oil temperature sensor is, especially in cold weather? The reason I ask is that my oil temp characteristics are pretty consistent with what was written above. However, one additional observation: on cool days especially, for example, when my gauge reads 70 degrees and I come to a stop sign, the gauge quickly (within a minute or two) runs up to 80 degrees; if I turn off the car it goes even higher. When I start driving again it will go down to 70 very quickly, on cold days down to 60; all within seconds/minutes. Can the temperature of your entire oil system really change that quickly? Or is it that some parts of your system, or just the air flow on and around the temperature sensor are causing your gauge to move around?

I use mechanical gauges and always check new gauges before installing them by placing the sensor in a pot of water on the stove (wifey just loves this), you can check the gauge up to the boiling point of the water, 212 degrees.........

I have 2 gauges on my race car, one in the oil pan and one in the remote oil filter AFTER the oil cooler.. I've never seen sudden changes in temp as you describe, but will see a slight rise in temp in the oil pan after shutting down the motor for some minutes before things start cooling off on their own, same with the water temp.

David

[fastd]

David,

How much temperature variation do you typically see between the two gauges?

[DAVID GAGNARD]

Originally Posted by fastd

David,

How much temperature variation do you typically see between the two gauges?

Not as much as I'd like to see!!!!!!!!!!!! Typically about 20 to 25 degrees when starting out in a 20 minute race, but, by the end of the race, the temp difference will be down to about 10 degrees......but, remember, this is a race car, 475hp,440 torque,(331 cu in stroker) turning from about 3000 to 7000 rpms on a road course for 20 to 30 minute races.........

The type of cooler and length of track will make some difference... tracks with longer straights will get more airflow thru the cooler longer and keep the oil 5 to 10 dregrees cooler than short, tight tracks where the rpm level is still up, but forward speed is not.......

On one particular short track, I've had oil temps of 265 after a very hard 20 minute race, but with one cool down lap, it had dropped to about 225 degrees by the time I came in off the track, I'm sure with another cool down lap it would have been about 200 or so......

On the race car, I'm o-k with anything from 200 to around 240.....I've run higher temps, but would rather it not go above 240, and with the oil cooler I'm now running, I think it should not hardly ever exceed 240 except on the most very hot summer days.....

I've tried at least 5 different coolers soo far and the best I've found is a trans oil cooler off a 08/09 Ford F-150 4x4 truck.... it's about 16 inches long and about 6 inches wide with a very good fin count, I've had similar size/shape after market coolers, but they didn't do as as good a job as the Ford factory cooler........

On a side note: I have a 65 Fastback with a 350hp, 351-W in it and it has a road race oil on it also,but NO oil cooler, it's a street car. Does have an oil temp gauge in the pan only.... The other day I went to work in it (200+ miles) and outside temp was from about 45 to 70 degress from daylight to mid afternoon.....On the highway water temp stays on 180 and my oil temp stayed on 180 also.... In town or when running it up thru the gears, oil temp will go up slowly to about 200,maybe 210 depending how hard and how many rpms I turn that motor (max 6000rpms).....once back on the open road, it took no more than 5 minutes of cruising speed to get the oil temp back to 180....

David

[ERA Chas]

David,
Great data and track performance.

Sorry to ask-"200+ miles" to work?? Round trip I hope??? YEESH-you get the Iron Butt award every day. I would work in a laundromat to avoid a trip like that.

[DAVID GAGNARD]

Originally Posted by ERA Chas

David,
Great data and track performance.

Sorry to ask-"200+ miles" to work?? Round trip I hope??? YEESH-you get the Iron Butt award every day. I would work in a laundromat to avoid a trip like that.

Yes, round trip,usually 200 to 250 miles, I make a gaint circle so to speak with about 8 to 10 stops,longest stretch is about one hour at a time, so it's not bad..........
you get used to the driving and I like being on the road and going different places vs. sitting behind a desk in an office all day.......

David