Engine Oil temperature

Engine Oil temperature

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Discussion

GTWayne

Original Poster:

4,595 posts

218 months

Wednesday 20th August 2008
quotequote all
This question is born out of BigBens question about engine temperature.
What do we deem a sensible oil temperature for a performance (not race) motor used mainly on the road. I have always thought that it wants to be roughly 10 degrees hotter than water temp but this can be difficult to achieve.

Steve_D

13,759 posts

259 months

Wednesday 20th August 2008
quotequote all
Depends primarily on which oil type you are using. A full sythetic will and should be much higher. We did this a while back on the Ultima forum and I don't have the figures with me at work. Will look them up later.

Yes the oil should be hotter than the water and yes it is difficult to achieve. On American V8 race engines they fill the water jacket right up to the level of the core plugs with a cement like material. This both strengthens the block and reduces the cooling in the low half of the engine.

Steve

Edited by Steve_D on Wednesday 20th August 10:15

350Matt

3,740 posts

280 months

Wednesday 20th August 2008
quotequote all
80°C + in the sump, ideally 100°C for most semi and full synths

Matt

Steve_D

13,759 posts

259 months

Wednesday 20th August 2008
quotequote all
Words from my reply in Ultima forum.

In a book by David Vizard he is saying that mineral oils are OK to a max 120 degrees C and that power is increased at these higher temps but that is mainly because the oil is thinner. Synthetics are a more constant viscosity across temperature so there is no significant gain to be had by running them hot. Synthetics are good for 150+ degrees C.
As well as lubrication the oil is acting as a coolant. The ideal temperature hear for a synthetic is 76-88 degrees C.

Steve

ridds

8,233 posts

245 months

Wednesday 20th August 2008
quotequote all
No cooler than 90 really.

Mineral good to 120 as said Synthetic bulk oil good to 140 happily, above that and I'd start to get wary. Things go wrong with synths above 150-160 get to 180 and you'll cook it very quickly.

Lube testing many years ago I was heating synthetic oil to 180 to acheive a 150-160 main gallery temp to then take oil samples from the head with the engine running at high speed to check aeration levels! The oil died a very quick death at those temperatures. laugh

knighty

181 posts

235 months

Thursday 21st August 2008
quotequote all
for mineral based oils, they will be quite ok to a maximum of 140 degC

for synthetic, max is 150DegC.

All major motor manufacturers test to, and sign-off all engines against these figures.......in short, dont be afraid to run the oil well into 100 degC.