Coolant temps vs Oil temps??

July 19, 2021, 01:06 PM

Anyone with an oil temp gauge able to compare how coolant temps compare to their oil temps? I don't have an oil temp gauge at the moment. Just wondering how far into a day of racing before the oil gets hot. Wondering on first warmup just how much difference there is between the two and how close they get during the day.

July 19, 2021, 02:32 PM

CURTIS REED

I use an oil heater plus run a diaper and it's harder than you would think to keep heat in the oil. I do have an aluminum pan though. I try to keep the oil above 160° at least. I prefer to see it at 180° but it's hard to keep it up there unless I'm hot lapping.

Just driving around with the lean out open I can build 150° in the water pretty easy and still won't have 100° in the oil.

July 19, 2021, 03:03 PM

banjo

I found it would normally take two passes to get good heat in the oil. Before I started monitoring it, car would be slow the first two passes before it would settle in.

Hot lapping. I have seen it get to 210-215, normally run around 185 for water temp.

My routine, is to plug the oil pan heater, get at least 120 degrees in it, go warm it up to about 200 degrees water temp. Bring it back to the trailer,plug the oil pan heater back in, and let it heat soak. I like the oil temp at least 180 when racing.

The problem with running slow off the trailer was definitely worse with thicker oil/high volume oil pump. Use to run 50 weight with hv pump. Now i run 10/30 with a standard volume.

July 19, 2021, 03:43 PM

TOP38

quote:
Originally posted by Eman:
Anyone with an oil temp gauge able to compare how coolant temps compare to their oil temps? I don't have an oil temp gauge at the moment. Just wondering how far into a day of racing before the oil gets hot. Wondering on first warmup just how much difference there is between the two and how close they get during the day.

They aren't really related! Coolant warms up much faster and also cools off the same. If you don't have an oil temp gauge use oil pressure as your guide during warm ups in the mornings. Oil pressure at idle is the best way to gauge oil temp without a gauge. I guess you could use a heat gun also if you are not running a diaper. Once you get oil temp vs oil pressure you don't need a gauge!

July 19, 2021, 07:36 PM

markemark

Depending on the cold engine temp at the first start of the day, water temp could be 140*+ and oil temp still not at 100*. I like to see 140* of oil temp in my initial start of the day. Using 93 octane to warm engine and EGT’s are in the 1000 - 1075*range. As soon as I switch to methanol the EGT will drop to 600*.

This Sunday , last run of the day (was 85* and sunny) water temp was 172* and oil temp 165* at start of burnout. 50 seconds later at 1/8 mile finish line water 174*and oil 188*. 15 seconds later water 175* and oil 200*. Oil can continue climbing to 210* entering my pit area. Using 10w30.

Engine and trans temp gauges are worth having imho. Or even a data acquisition with this information.

July 19, 2021, 07:49 PM

Eman

What oil heaters are you using? How hot does it alone get the oil? I've got a stick on pad heater on the bottom of the oil pan and a diaper.

July 19, 2021, 08:43 PM

CURTIS REED

Will raise the temps to 150 easy.

https://www.moroso.com/oil-preheater23991/

July 19, 2021, 09:00 PM

Big Steve

quote:
Originally posted by CURTIS REED:
Will raise the temps to 150 easy.

https://www.moroso.com/oil-preheater23991/

After burning out multiple stick on heaters I installed this Moroso cartridge heater in the pan and have not looked back. I can heat 10qts to about 150 in about 30 minutes

July 20, 2021, 10:57 PM

Eman

As I said for now I don't have an oil temperature gauge but I have a pad heater on the oil pan. Anyone have a gauge and monitor how hot their oil got with a pad heater on the pan?
I see many with freeze plug heaters for heat but I'd say it's not doing much for oil temps. just like my oil pan pad doesn't raise coolant temps.

July 21, 2021, 08:14 AM

green1

I used to have oil temp gauge years ago and found out oil temp followed water temp just lagged. If I cooled motor way off the oil would follow as soon as I fired the motor up. I don’t monitor it any more. Just get motor good and warm before first run then let it eat.

July 21, 2021, 10:24 AM

NC3x58

quote:
Originally posted by green1:
I used to have oil temp gauge years ago and found out oil temp followed water temp just lagged. If I cooled motor way off the oil would follow as soon as I fired the motor up. I don’t monitor it any more. Just get motor good and warm before first run then let it eat.

Same here. I also make sure I do my best to get the motor good and hot during warmup and let it heat soak for right around 30min-1hr before making my first run. After that, I don't worry about it too much.

July 21, 2021, 10:31 AM

RPROGAS

Our two older sons ran late model circle track cars for decades where qualifying was a critical issue. Their cars always qualified faster when the oil was hot and the water was cool.

Bob

July 21, 2021, 01:32 PM

green1

quote:
Originally posted by RPROGAS:
Our two older sons ran late model circle track cars for decades where qualifying was a critical issue. Their cars always qualified faster when the oil was hot and the water was cool.

Bob

My engine builder always said you make the most power with hot oil and cool water but that’s hard to accomplish because the oil is in the block and will follow water temps.

July 21, 2021, 01:43 PM

CURTIS REED

quote:
Originally posted by green1:

the oil is in the block and will follow water temps.

It doesn't work that way for me.

July 21, 2021, 01:50 PM

Triple Nickel

Had an oil temp gage in my car first fast car. What i learned was that oil temp is a function of load on the motor. If the motor is just idling, the oil temp won't come up quickly if at all and may never reach actual operating temp like it will after the first pass down the track. I learned to heat the motor up quite a bit higher but not by turning the pump/fans off, rather i would load the motor more via driving down the return road progressively getting more and more throttle involved as i made laps up and down the shut off area and return road. If i got there late and or track shutdown area was not available for warm up, i'd ride slowly around the pits in high gear dragging the brakes while holding the motor around 2000 to 2500 rpm in gear. Depending on your setup, option 2 is hard on brakes.

I did see differences in out of the trailer performance when i was able to get the oil temp up to normal operating range prior to the first round run on 3 day events when we didn't have a time trial. If i was able to get the oil nice and hot and simulate full pass temps, the car ran very close to previous day ET's, appeared this was the biggest influence in if it would run the same number or not when compared to the previous day.

Get EVERYTHING good and hot, not just engine oil temp, but trans, rear end etc. It matters if you don't have a time trial and trying to dial honest.

July 21, 2021, 02:32 PM

TOP38

quote:
Originally posted by green1:
quote:
Originally posted by RPROGAS:
Our two older sons ran late model circle track cars for decades where qualifying was a critical issue. Their cars always qualified faster when the oil was hot and the water was cool.

Bob

My engine builder always said you make the most power with hot oil and cool water but that’s hard to accomplish because the oil is in the block and will follow water temps.

From a power view point, yes, otherwise NO! After a run your cooling the water way faster than the oil cools, add a diaper, fenders and a hood, the oil doesn't cool very much between rounds!

July 21, 2021, 02:40 PM

TOP38

quote:
Originally posted by Triple Nickel:
Had an oil temp gage in my car first fast car. What i learned was that oil temp is a function of load on the motor. If the motor is just idling, the oil temp won't come up quickly if at all and may never reach actual operating temp like it will after the first pass down the track. I learned to heat the motor up quite a bit higher but not by turning the pump/fans off, rather i would load the motor more via driving down the return road progressively getting more and more throttle involved as i made laps up and down the shut off area and return road. If i got there late and or track shutdown area was not available for warm up, i'd ride slowly around the pits in high gear dragging the brakes while holding the motor around 2000 to 2500 rpm in gear. Depending on your setup, option 2 is hard on brakes.

I did see differences in out of the trailer performance when i was able to get the oil temp up to normal operating range prior to the first round run on 3 day events when we didn't have a time trial. If i was able to get the oil nice and hot and simulate full pass temps, the car ran very close to previous day ET's, appeared this was the biggest influence in if it would run the same number or not when compared to the previous day.

Get EVERYTHING good and hot, not just engine oil temp, but trans, rear end etc. It matters if you don't have a time trial and trying to dial honest.

Point about oil temp moving up faster with engine load is 100% dead on.

Not sure why everyone has these elaborate means to heat engine oil up. Idle oil pressure is all you really need to know. Typical summer deal, run engine 5 to 10 mins with intermittent load periods until idle oil pressure is 45 - 50 PSI, done! For my combo this equals about 135 degrees F. I let the water get to 170 or so during warm up, shut it off and let it heat soak!

July 21, 2021, 04:12 PM

markemark

If you use 10w30 or straight 30w I believe you’ll see an improvement in consistency over using 20w50.

July 21, 2021, 04:39 PM

Canted Valve

quote:
...until idle oil pressure is 45 - 50 PSI, done!

To offer a little perspective on oil heating/thinning and pressure, here is how my motorcycle acts. V-twin, 1100cc, Yamaha V-Star, SOHC's. This engine feeds the bottom end first, then with "left over" pressure it feeds the oil filter (yes only partially filters oil volume) then pumps oil up to the cams/valves/springs. Using Mobil 1 20w50 in this air cooled engine (the owners manual calls for semi-synthetic 20w40) the initial start up pressure is around 50 psi. I installed a custom oil gauge (it has none from the factory, just and idiot light for oil level NOT pressure) after the filter and at the juncture where the oil goes up tubing to the top end. How do I know when the oil is heat soaked? The gauge reads 0 (zero)!!! No kidding! Naturally I about freaked out and started looking deeper. A second 0-60 psi gauge gave the same results. So I put Lucas straight 60W in it, same result. I bought a new 0-15 psi fuel pressure gauge, same result. Well maybe 1 or 2 psi, maybe not. Went back to 20w50 and that's where it stands 5 years later and all is well.

July 21, 2021, 06:38 PM

FootbrakeJim

100% agree with Top38 & Triple Nickel on the effect of engine loading on oil temps. Diving a bit deeper into that, what particular aspects of increased engine load cause oil temp to rise?
More load = higher EGT's, which heats the head castings more. Probably not enough to drastically raise oil temps. My gut instinct always thought it was mostly the higher combustion chamber temps, (Meaning the oil that was thrown at the bottom of the piston crown, and on the upper cylinder walls absorbed the most heat). A few years back, I read a statement by a VERY reputable source, saying the single greatest factor in elevated oil temperatures is the Valve Springs. This completely surprised me, and made me think about it some more. In my mind, valve spring load does not really increase with engine load - the spring pressures do not increase with a higher throttle setting, etc. But they definitely do get hotter with increased RPM. (Increased RPM does not necessarily equal increased engine loading). A cold engine set at a fast idle does warm up the coolant more quickly than a slow idle. But I don't necessarily believe RPM alone is raising the oil temp a bunch. Anyone got any thoughts on what it is about engine load that more quickly raises the oil temps?