35i Oil temperature and speed to warm

simnew · Post by **simnew** » Sun Mar 24, 2024 11:19 am

Hi everyone,

I’ve had my 3.5i for just a year now and it’s been running well. It is a car from late 2009. What I have noticed (particularly compared to my B58 engined GranCouple 440) is that the oil temperature does take quite some time to move. I would say unless you drive for 15 minutes it doesn’t appear to move. On a longer journey it seems to hover between 90 and 110 max and I think the heater is slow to really warm the car in winter. It has had a new radiator fairly recently and I was wondering if perhaps the thermostat is stuck open or something. What experience have you had with the N54 and warm up times ?

Busterboo · Post by **Busterboo** » Sun Mar 24, 2024 1:28 pm

It's slow to warm up.

I live where I can drive fast within a few minutes of my house, but never go above 3k revs until the engine's hot, which is much more than 15 mins.

ronk · Post by **ronk** » Sun Mar 24, 2024 2:27 pm

Same drill for me and only light throttle!

people are used to water temperature gauges in their cars - coolant heats up quickly and the gauge also shows running temperature very quickly.

Chippie · Post by **Chippie** » Sun Mar 24, 2024 3:35 pm

Your oil warm up seems about normal, do you know if the water pump has been replaced as these tend to fail around 70000 to 90000 miles so it may be precautionary to change that and the thermostat while you are on with it, after changing mine I did notice that the car ran slightly hotter under light use.

fatbaldboy · Post by **fatbaldboy** » Mon Mar 25, 2024 6:47 am

I notice the same.

Re the heating being slow to warm the car I think the heater waits until there's warm air to be blown before 'really' blowing - at least that's what mine seems to do.

This would obviously match up with the slow to heat-up engine you mention.

simnew · Post by **simnew** » Mon Mar 25, 2024 9:18 am

Thanks for your inputs. Yes it had a new water pump but not sure about the thermostat. Does anyone know how the thermostat works - I assume it’s not electronically controlled but I am not the most DIY when it comes to the engine bay

tiglon · Post by **tiglon** » Mon Mar 25, 2024 9:56 am

Mine is probably more like ten minutes to warm up to 90, but that depends on whether you're stuck in traffic.

90-110 seems low, mine is around 110-120 once fully warmed up, it definitely never goes back down to anywhere near 90.

simnew · Post by **simnew** » Tue Mar 26, 2024 12:16 pm

I think I will do a test run where I measure the temperature over time. I guess my worry is that maybe the thermostat is open on startup when perhaps it should be closed ? This would slow down warm up and also increase fuel consumption i reckon..... It does get to 100 maybe even 110 on a longer run. I was on a run down to Bath and back last week and that was a nice test and gave the engine a bit more run which can only be a good thing. Amazing how different the N54 with DCT operates so differently to the B58 plus ZF8. The N54 and DCT really likes to drive more on torque whilst although the B58 and ZF also does this, it is so much more playful in changing down and revving. Both amazing engines...

B21 · Post by **B21** » Tue Mar 26, 2024 2:48 pm

The N54 is a big heavy lump..it’s the worst of all worlds..in winter takes forever to get up to a decent temp..conversely pressing on through twisties / hills in summer it can soon go last 120c..

I doubt the thermostat has failed..

If you want the DCT box to be more ‘playful’ then look at xHP..gerarbox re-map tool..it’s the biz..

matsmith749 · Post by **matsmith749** » Thu Mar 28, 2024 2:14 pm

Hmmm.

Mine is also pretty slow to get the oil up to the midpoint (ish) of the dial - maybe 10-15 minutes, even longer if just chuntering around town.

But the heating is pretty good much quicker than that - I'm not sure what the link is to oil temp & the heating? I always thought that the heater circuit was more to do with the water temp, which gets up to speed way quicker than the oil (but we have no guage for that).

I get nice warm air after maybe 3 or 4 minutes into a journey.

B21 · Post by **B21** » Thu Mar 28, 2024 3:53 pm

B58 has insulated panels on the engine specifically to aid engine warm up..N54 doesn’t..

Water temp and therefore heating will lead oil temp by many minutes..

fatbaldboy · Post by **fatbaldboy** » Thu Mar 28, 2024 4:00 pm

matsmith749 wrote: ↑Thu Mar 28, 2024 2:14 pm I always thought that the heater circuit was more to do with the water temp, which gets up to speed way quicker than the oil (but we have no guage for that).

Good point! I'm so used to cars showing water temp I conflated...cars!

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