Quote:
Originally Posted by BEAR-AvHistory
Will positively guarantee you can't get 7 quarts of oil up to temperature in 2 miles even in Saudi Arabia.
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This is what I question, living with an N55, can't see how other N55 engines or the B58 can be much faster heating up. If anything, as petrol engines become more efficient, heat up will be slower, as there is less waste heat. We start approaching diesel warm up times, which we know are even slower, due to better thermal efficiency,
Being a diesel owner, I'm used to oil taking as much as twice the time to heat as coolant, particularly slow in winter months where even after 16 miles, oil is not up to temperature. When I took on the 535i, I was expecting much faster ECT heat up than a 3-litre diesel, with oil temperature still lagging well behind the ECT.
Was surprised that ECT is still quite slow to warm, oil is just a few degrees behind, and virtually levels out as the N55 engine's ECT reaches close to optimum running temperature.
Looking at the design I put the faster oil heating, (at least partly) down to how the oil sprays the underside of the piston crown, acting as a heater to the oil in the warm up phase. That in turn slows the ECT rise, as more of the available waste heat goes to the oil directly.
BMW haven't given as much detail on the B58 oil circuit as the N55, but imagine it will be similar for heat control.
If users are really getting to full temperature in so few miles/minutes, (my 5-series takes at least 12 miles/15 - 20 minutes, when the ambient temperature is below 10C/50F to get to optimum running temperatures), what's the mechanism for doing so, other than using more fuel?