As some of you know, a few months ago I removed my oil cooler from my 2005 XK8 because of 20yr old oil lines.
I recently installed the ( VDO - Temperature Senders M14x1.5 Oil Temperature Sensor / Drain Plug - 323-055) so I could read actual oil temperature in the oil pan. Using gauge and engine diagnostic tool my son and I tested it this weekend when outside temp was 91 deg. F.
While driving through the country for several miles at about 45 mph the temperature will eventually get to 210 deg. Then drove about 8 miles at about 55-60 mph too town while on the way the temp stayed about the same. After 2 slow circuits around town the temp got up to 237 deg. and after 2 more laps around town the temp didn't get any higher.
As long at the oil cooler is absent I will always have the gauge for safety's sake. I am running 5W30 full synthetic oil. The code reader reads temperature on front of engine next to oil filter where it is in aluminum block exposed to moving and get a reading about 25 deg cooler than oil pan. I'm going with the higher number of gauge for safety.

Question is, how hot is too hot for the engine.

Jack

 

We have two cars with V8 and V6 engines and oil temperature gauges. In both of them the normal oil temp is between 95 and 105 degrees centigrade which corresponds to your 210 degrees. Under extreme conditions I have seen the temp rise as high as 250F / 120C for short periods.

It sounds as if you are in the right range.

Richard

 

This bodes well for the NA cars, however, the story may not be so for the supercharged XKRs.

Did you happen to have baseline readings from when you had the cooler? What is the ambient temperature where you live?

 

The first test was done in the fall of last when the temperature was in the low 80's F. Temperature was monitored using a code reader. Later found that the sensor that the DCM uses reads the temperature from 10 to 20 deg lower than the sensor that I use in the oil pan.

The outside was in the low 90's when I did the last test and I'm going with the higher temperature that I got from the gauge that I installed just to be on the safe side.
I wouldn't think of removing the oil cooler from an XKR for obvious reasons.
Today we went for a long drive, gone all day. We sat in traffic creeping for about 20 minutes (there was a transfer truck burning in the road). I left the engine running while monitoring oil temp. 91 degrees air temp. oil temp went to no higher than 239 degrees.
As long as the oil cooler is absent the gauge will be present. I feel safer with gauge and no oil lines than with no gauge and 20 yr old rotten oil lines.
I also wouldn't recommend anyone do this. I know the risks but am being very careful.


Jack

 

230 F oil temperature is about what I get when the air temp is 105+ F and the car is stuck in traffic for 5+ minutes.
(2002 XKR) and the coolant gets up to 210-215 F


mostly it’s the coolant temp plus 15-18 degrees F


Z

 

Zray, I'm thinking if the temperature never gets above 250F it shouldn't damage the engine. If anyone disagrees with this please tell me. I'm sure it won't hurt the synthetic oil.

Jack

 

What coolant temp was observed when your oil temp was 239 F ?

Z

 

I don't have a coolant temperature gauge.

Jack

 

If you plug an OBDII reader in you can watch it in real time while driving. I did that the other day just to see the cars behaviour, it does warm up very fast and hits max of 94/95C at 60mph, if you drive faster about 70mph or more it drops down to 85 ish C. I have an XKR though which will run much hotter then the none supercharged cars, the intake temperature is around 24-35C though depending on the air temp. Before I fixed my intercooler though the intake temperature was over 60C.

 

When we used the OBD11 reader I didn't check coolant temp. It did however read Oil temp while driving around in town at 212 deg F which is probably wrong. I think the high 230's that my gauge said would be more accurate, but maybe not.

Jack

 

My 2002 XKR exhibits the same pattern of running cooler when the mph is over 75-80. Especially cooler running when the over / under is 60 mph vs. 85 or 85+ mph.

The coolant may start to heat up more at speeds over 130 mph, I don’t know. As that’s when my aged reflexes are not up to the task of this type of scientific curiosity.

Z

PS: the oil temperature is also hottest at these slower speeds. Clearly , not much testing was done sitting in traffic vs going flat out
…not that I blame the engineering team on that score…..

 

My XK8 runs at about 210F on the road no matter how hot it is, just gets hotter at the very slow speeds or sittng still in traffic. I also noticed While near Banner Elk near Boone NC on very hilly roads running up and very steep hills at 35 mph the oil temp went up. That might be when I would need an oil cooler. When my testing is done this fall I may decide to repair my hoses and put the oil cooler back on. That is if I can make it trustworthy.

Jack

 

That’s somewhat hotter than my 2002 XKR.

a convincing argument can be made that the XK8 has the more highly
tuned engine vs the XKR until some boost is made. With variable valve timing and more compressIon it’s understandable that the XK8 might run hotter, at least at lower RPM.

We would need a few hundred owners performing the same tests to have a
determination of any kind

all in all, these are interesting cars.

Z

 

I agree

Jack

 

It would probably be the same with most cars even higher performance cars then ours, faster driving means higher airflow but at lower speeds the fans will kick in and they are likely sufficient to keep the coolant and oil from overheating at least unless you are sitting at a standstill and revving it for no reason? Even when I had the number plate removed the temps wheren't much different in my observations anyway so I think it's relaly just air speed more then any real restriction in the design although it would be nice to have a better number plate position. It might be a problem if you are driving in a hotter climate then the UK but whenever it hits 30C in the UK my temps are roughly the same as when they are when it's 20C. It did hit 41-42C a coupl eof years ago and the car did fine then as well although I didn't check my coolant and intake temps. These are fast cars esspecially the XKR so I think just driving faster is a good idea

 

There doesn't seem to be any difference in oil temp when the Ambient temperature differs as much as 20 degF.. As I said earlier the thing that really get the oil temperature moving up fast is going slow on a hard pull up hill. Working engine with very little air flow and this is where an oil cooler
would probably come into play. Can't see that the cooler would do much with car at a stand still except for the small amount of heat that the cooler would radiate in the still air.

Jack

 

I have, and it depends on how you got to the 130 mph. If you were flooring it, the coolant temperature will be between 215ºF and 220ºF. However, if you steadily crept up to 130 and stayed there for a few minutes, the temperature drops to about 205ºF, this is at ambient temperatures between 85 and 94ºF. I have also seen coolant temperature drop from 205ºF to 190ºF on a steep, extended, downhill incline, at night, at 90 mph with ambient temperatures of 78ºF.

This is going from data from the RealGauge modification. I don't have any data regarding oil temperature on my car.

 

Yea I did notice actually doing 40mph up a hill the coolant temps went up a fair bit I should think the oil went up too although it was a short hill. Best to go up hills fast I guess.