Oil temp cooler after service?

raykelly · Mar 20, 2017

Is it just me or has anyone else noticed this....
I changed the oil and filter last week and noticed that my oil temp sits about 10degrees lower now than it did before service. (considerable difference!)

Service Background:
Car was serviced in Jan 2016. I serviced it last week with 8700 miles driven since last service. Im using Mobil1 0w-40 with filter from Porsche.

Before service:
My Oil temp would sit just below 90 degrees during normal driving.

After Service:
My oil temp seems to be sitting below 80 degrees during normal driving and then with spirited driving goes just above 90 degrees.

Am I only dreaming this or has anyone else experienced this?

Does this mean that maybe a different oil was used in last service... or maybe it wasn't even serviced!

thanks!

Lancerlot · Mar 20, 2017

It's more likely there is less water vapour in the new oil to heat up.
Regards,
Clive

raykelly · Mar 20, 2017

I was thinking it might be impurities in the oil. Surprised to see such a difference in temp. Interesting to see how long it takes to behave like it did before oil change. Could be used as an indicator to change the oil.

Lancerlot · Mar 20, 2017

It depends on usage. Moisture builds up more with a lot of short journeys.
Long journeys bring the engine up to full working temperature for sustained periods, allowing moisture to evaporate.
Regards,
Clive

raykelly · Mar 20, 2017

Yes, it makes sense. Thanks Clive.
I will keep an eye on it and see how it goes. I do very short journeys (school run) but with at least 2-4 long journeys every month.

Never had an oil temp gauge before on any car. So its good to see an improvement after oil change!

bandido · Mar 20, 2017

Different car but I changed the oil in my 981s before Christmas at around 28,000 miles about a year/10,000 miles after the dealer service and found the engine running about 2-3 degrees cooler at 90ish.
I don't remember a similar fall after the 20k dealer service (and I watch).
I flushed a litre plus through when changing.
My use profile hasn't changed-no cold runs, typical outing 30-50 miles enthusiastic.
Ambient isn't really a factor (constant use before and after through the early winter). I have noticed that speed/airflow don't seem to be factors but revs are. Slightly counter-intuitively, decent (not really high) revs (even at lowish speed) seem to reduce the temperature reading. So presumably pressure related...
10 degrees sounds like a big drop to me.
My 997 used to run at 90 with very little variation but it also used oil.

raykelly · Mar 20, 2017

Bandido, I thought 10 degrees was a lot too. I just hope that it is running at an optimum temp for the engine now. Thanks for your input. I will be watching it over the coming months to see how it behaves and if it changes. My car over the 10 month ownership has used 600mls of oil. Topped up twice, 300mls each time at 3500-4000 mile intervals over the 8700miles from previous service. So not a lot of oil and a lot less than Porsche suggest. Its a lot less than my BM330i would burn. It used to burn 1 litre between my 10Kmiles service.

I didn't do a flush when changing the oil, however, I did remove the oil from the filter housing and let it drain for over an hour. The oil was around 60-70 degrees when I changed it. It then took 8litres to fill it.

s2rjn · Mar 22, 2017

I had my oil changed last Friday (had a major including plugs) and have noticed a similar thing, it seems to take ages for the oil to warm up! Yesterday I drove for 30 mins at motorway speed and it was barely above 70 degrees? I'm wondering if there is a fault with the temp sensor perhaps, I've tried to take an oil reading and when it manages to do it I have 4 full segments but at other times it won't read it saying 'engine not warmed up'
ive never noticed this is my previous cars following oil changes so I am thinking I my have a sensor problem as it was always at 90 before the oil change and I can't imagine the water content caused it to be like that as I drive 30-40 miles on the M4 everyday so going by the previous post the water content should have evaporated surely ?

anyone think It could be an oil temp sensor? how difficult are they to replace?

raykelly · Mar 22, 2017

Thats really low and a bigger difference than mine. I have gone through numerous posts on the net. It seems normal temp is between 80 and 90 degrees. Also widely agreed is that the gauge is not a true reflection of the oil temp. To get the actual temp, you need to go into your OBD port. Which is something I will do when Im home at the weekend. Just to see if there is a difference in reading.

When you try to get a oil level reading.... are you doing it after your 40mile run? If it's coming back that the engine is not warm enough then its definitely a sensor.

I wanted to know the optimum oil temp for Mobil1 but could not find it. If it was 90 degrees then my oil is not at the optimum temp to protect the engine and causing unnecessary wear. I am guessing that mine with a temp of 78degrees is suffice and could be even better especially if I drive hard now and it sits at 90. Im putting mine down to improved oil flow due to the oil and filter change. Or maybe my temp sensor is failing also!!. Mine will eventually go to 90 but it is with enthusiastic driving. My oil heats up as normal (after 10-15miles), its just the final reading is wrong (or could be correct) with mine.

Let us know what you find out.