On my 03 S I have been noticing over the past 2 days that only in the morning when I am driving to work the oil temp gauge will go between 110°C and 120°C. it will change at least 15 time on the drive in (45 min drive). The 1st day it happened it went up to 140°C for about a minute. On the way home the temp will stay around 108°C. The oil level is still full and it was changed a little over a month ago.

Any thoughts on this would be appreciated.

 

Ever rear Randy' Webbs article on SC pulleys?
He found that since the factory oilcooler was just a small loop with coolant going through it, if a pulley was beaing run, and a lot of rpm's were causing a bit of cavitation, oil temps would quickly go up, while the iron block/head would absorb most of the heat....
I'm not sure if you are running a pulley, or if you were running high enough rpm's to cause cavitation...but the stock waterpump does have plastic impellers...so maybe with a bit of wear, cavitation is happening at lower rpm's....also could point to lower radiator preasure...meaning a bad cap, since the higher the psi of the cooling system, the less likely caviation will occur....of course it could be related to the grounding of the temp probe, the thermostat......who knows....but an interesting question to ponder!!
Just remember...oil temps are kinda related to radiator temps if you have the factory cooler.....
I guess the radiator temp is normal...steady right. If it is swinging too...then the whole premise of the question changes....And the possible causes!!

 

I haven't read that article. The pulley has not been upgraded at all and haven't been running high rpm's. So would your suggestion be to look into the cooling system? The radiator temp stays steady all the time.

I will just go purchase another cap and see if that helps. The one part I wonder is why doesn't it seem to happen all the time.

 

Well...on a stock car, no pulley....I doubt it is cavitaing...especially at normal rpm's....maybe you are seeing a side effect of the thermostat opening and closeing...changing the temp of the coolant cooling the oil....as long as the required changes has been done to the fluids...coolant and oil...I would just watch it....and wait.

 

Are the oil temp fluctuations you noticed happening while steady driving or stopped in traffic ?

 

I have been watching it closely and it still seems to be doing it. It's been happening when steadly driving.