Oil Temp

[tiglon]

Just curious as to what oil temp other N54 owners limit revs until, and what they limit the revs to?

If I remember correctly, Andy said he limited it to 2k/3k revs until 105 degrees. A few members on other BMW forums say 3k revs until 90-100 degrees, and a lot quote handbooks that say "around 10 miles" (seems an odd way to measure it when you have an actual oil temp gauge!).

So far I've been leaving the gearbox in full auto and being gentle with the throttle until at least 100 degrees, which means gear changes before 3k revs, and have been super-gentle with the throttle until the needle gets to 90 degrees. I doubt I'll change that policy regardless of what others do as there's no need to take the risk, but it's interesting to hear others' thoughts on it anyway.

 

[oilman]

The additives in an engine oil come alive at around 70degc. In a modern petrol car it takes around 7-10 miles of normal driving to get the oil up to full temp, usually 90-100degc.

Cheers,

Guy

 

[SV8Predator]

The additives in an engine oil come alive at around 70degc.

"Come alive"? What does that mean exactly?

 

[Smartbear]

The additives in an engine oil come alive at around 70degc.

"Come alive"? What does that mean exactly?

I’d guess that the detergent additives start working above a certain temperature?
Rob

 

[oilman]

The additives in an engine oil come alive at around 70degc.

"Come alive"? What does that mean exactly?

My apologies, this is a basic way to look at it but think of engine oils as having different additive packs in them that do their thing at different times, one takes care of start up (where 80% of engine wear occurs) and another for the warm up process and then another one when the oil is up to temp for normal running, potentially long periods at a time. A bit like a relay race, one additive pack hands the baton over to the next for optimal protection as both the oil and engine get up to target running temp.

The warm up additves start to hand the baton over to the hot running additves at around 70degc.

It is obviously a lot more complicated in reality, but thats the nuts and bolts of it. Quality engine oils are a very fine balancing act to do everything they need to do, when they need to do it, over and over again.

Cheers,

Guy

 

[Anonymous]

The warm up phase is mostly two related issues..

To let oil circulate freely and fully around the engine and to reduce thermal shock on internal components…

So the key point is to get moving quickly after start to allow a steady rate of climb of temperature without imposing any significant stress or load on components..

So 4K on a light throttle is a lot better than say 2k on a heavy throttle.

With modern turbo’d cars peak torque and peak load on pistons and rods occurs early in the rev range ..so a light throttle is the key point and no lugging ..given the bountiful torque of the N54 that is not that hard a task.

The oil temperature is a good indicator of balanced thermo dynamic loads as when it’s above say 70c it indicates the bulk of the engine has warmed up and then extra loads are not going to substantially and quickly effect the physical state of the engine.

The graph shows how viscosity is affected by temperature…shows why thrashing an S54 engine from cold is not a good idea..

So somewhere after 70c which is when the oil temp needle is really of the needle helps a lot..anything after that is nice but not compelling..

Overall it’s important that the internal oil temperature not what is measured exceeds 100c for a period of time to boil off the water based products accumulated during the start up phase..

 

[Argyll Andy]

Will, maybe I let it warm up a bit more than it needs to be but at least you know in my hands that it didn’t suffer from the strains and stresses pointed out in your replies about being revved too early :wink:

90-100 seems to be the common consensus, I think I let it reach 100 so you can maybe drop a bit if you wanted too. Doesn’t seem like it would be detrimental if you chose 90 instead of my over cautious 100

 

[tiglon]

Some really interesting information there for a mechanical idiot like me, thank you

Just need to avoid the temptation of using it for short journeys...

 

[mcbutler]

N54 can spin crank shells if you nail it when its cold, i drive mine lightly till around 90deg

 

[Mr Tidy]

Well firstly thanks to "tiglon" for posting this.

It prompted me to start a similar thread about the E85/86 M cars.

And it seems the S54 and N54 have a few issues in common! Like the potential to spin crank seals if nailed from cold. :roll:

 

[tiglon]

Well firstly thanks to "tiglon" for posting this.

It prompted me to start a similar thread about the E85/86 M cars.

And it seems the S54 and N54 have a few issues in common! Like the potential to spin crank seals if nailed from cold. :roll:

Fortunately this thread hasn't descended into :violent1: - yet!

I would imagine most performance engines need to be treated with care when cold, but as mentioned earlier I am mechanically ignorant so that's just an assumption. My faithful daily donkey Ford Focus 1.0 on the other hand enjoys being given a good beating every day - first thing on a cold morning for the first 5 miles it's definitely faster than the neighbour's McLaren

 

[Mr Tidy]

Fortunately this thread hasn't descended into :violent1: - yet!

No - that wasn't exactly what I had hoped for!

But if nothing else it has been entertaining. :wink: