While on the topic of oil changes and only slightly off topic this may be of interest to some of you.
I recently took a car for mapping on behalf of someone else and noticed that the oil pressure was very slow to reach full pressure of around 6 bar. This was of some concern to me. The power figure achieved was very poor, 336 bhp using a turbo that had produced 392 bhp and the mods on both cars were similar. The car was fitted with oil pressure and oil temperature and the oil temperature never exceeded 55C all the time I was in the car. Anyway, on return home I suddenly noticed there was no oil pressure and stopped immediately and waited for several hours for the recovery flatbed.
On checking the car the following day I concluded it was very unlikely there was no oil pressure and after investigation and the use of an alternative guage I found the fault actually lay with the guage or sender unit but pressure was still very lazy to rise taking perhaps 10 seconds plus from cold to reach normal pressure on tick over. On further investigation the car had an adaptor plate where the OE oil filter is located and the filter was now relocated in the inner wing so there was a considerable length of additional oil feed and return pipe.
Further investigation showed the car had mega leak downs but the sandwich plate was removed and the oil system put back to original with the oil filter where it was supposed to be. Full oil pressure is now achieved a few seconds from turning the key but unfortunately the engine has been removed from the car as it had mega leak downs on test and now needs a rebuild.
I come across numerous Classics with aftermarket oil filters and these are just not required on most of them but the owners misguidedly fit oil coolers without first checking what actual temperatures their oil achieves. Typically Classic's will run around 80C or a bit more on oil temperature and in similar conditions New Age are generally 10 degrees or a little more as are all 2.5s. The oil manufacturers advise that the top temperature for their oils is 140 deg.C. which seems high to me but they will know more about oil temperatures than me. On track, I can only remember stopping twice for oil temperature reasons, both on a Classic producing close to 600 bhp on race fuel and I stopped when the oil temperatures reached 125 C. Both occasions were on very hot Summer days, once the hottest day of the Summer actually.
Now if you look in some VW, Audi or Porsche you will see they have oil temperature guages as standard and the red line is at 140C.
Running low oil temperatures greatly shortens the life of the engine just as poor pressure or lubrication on start up will do and I note that Castrol claim that 75% of engine wear takes place on start up.