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Old 04-18-2019, 08:47 AM   #1 (permalink)
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Pre heat transmission?


I drive a Audi diesel, aut. Quattro (4wd) and I have two onbord Computers making me abale to messure my mpg avarage by trip and between fuelings.

I have notised that when I cold start my Car (with engine preheated) I obtain a fuel cosumtion that is 7.2l/100km in average o er a distans of 88km. This is in The morning and temperaturen are around - 5 to zero degrees C.

When I take The return trip I have an average fuel consumption of 6.1l/100km. I drive home in The afternoons and temperaturen is ofen around +10 deg. C.

I starten to think that the higher fuel consumption in morning depend on The oil temperatur of The aut. Tranny. I wounder what do you think about preheating The oil in The Tranny and how is The best way of doing it?

Tanks /Z

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Old 04-18-2019, 09:03 AM   #2 (permalink)
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Temperature affects both engine AND transmission, and preheating either of them helps. There are bigger gains from preheating engine oil but if you're going to get an oil pan heater you might as well heat both engine and transmission.

In my car, I have a coolant heater, oil pan heater and transmission heater.
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Old 04-18-2019, 09:52 AM   #3 (permalink)
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It definitely is important. I started a thread a while back about using engine coolant to heat the transmission. Mine was thinking about manual transmissions, but automatics are even more temperature sensitive. Most automatic transmission coolers are also warmers where the engine coolant helps heat the oil, but once it is up to temperature, it also cools it down.

Anyway, here is a link to my thread. There are several links to studies done on the effect of transmission oil temperature that you can check out.


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