07-26-2020, 04:38 PM | #1 |
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Witch differential oil should I go with?
Hey everyone, currently running the stock bmw oil in my rear diff, saw on ECS they sell liquid molly diff oil and was thinking of swapping it quickly. How much fluid fits in the diff? Is it as simple as dropping the plug and refilling it?
Was gonna use liquid molly Hupoid gear oil 85w -90 as its meant for track use witch I do. Thanks guys!
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16 M235xi 8ZF Black on Red FBO: Xhp trans tune -BMS Intake - VRSF Catless DownPipe - VRSF CP - VRSF Muffler delete/resonator - n22 plugs - MHD stage 2+ 95map - Wagner EVO II Preformace IC - Rear seat delete - weight reduction/stripping -FTP 18.5in rims - Hawk HPS front pads - StopTech STR 660 fluid
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07-26-2020, 09:28 PM | #2 | |
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On the M240xi we don't have drain plugs only fill plugs which makes the process more difficult. You need a pump to suck the old oil out and then to refill it. Your car is probably the same. You just slowly fill it until it starts to leak out of the fill plug. |
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07-27-2020, 10:50 AM | #4 | |
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75w140 oils at 120C have a similar viscosity to 75w90 oils at 100C and with some cars you may see diff oil temps up to 130 or 140C on the track. Be aware oils such as Redline No-Shock range compared with the normal range with LSD additives or NS range without LSD additives may cause problems due to the grease-like polymer additives. |
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07-27-2020, 10:55 AM | #5 | ||
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16 M235xi 8ZF Black on Red FBO: Xhp trans tune -BMS Intake - VRSF Catless DownPipe - VRSF CP - VRSF Muffler delete/resonator - n22 plugs - MHD stage 2+ 95map - Wagner EVO II Preformace IC - Rear seat delete - weight reduction/stripping -FTP 18.5in rims - Hawk HPS front pads - StopTech STR 660 fluid
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07-27-2020, 10:59 AM | #6 |
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Depends on what diff temperature you are seeing on the track, anything under 100C and the 75w90 is fine. Have to put temperature strips on the casing or use and infrared thermometer to determine. If the car is stock power and you don't have an LSD fitted, it shouldn't get too hot. Also depends on how long you run, the ambient temperature and the times between sessions to allow the diff to cool down. 20 mins of hard running every hour lets the diff cools quite a bit.
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07-27-2020, 11:01 AM | #7 | |
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16 M235xi 8ZF Black on Red FBO: Xhp trans tune -BMS Intake - VRSF Catless DownPipe - VRSF CP - VRSF Muffler delete/resonator - n22 plugs - MHD stage 2+ 95map - Wagner EVO II Preformace IC - Rear seat delete - weight reduction/stripping -FTP 18.5in rims - Hawk HPS front pads - StopTech STR 660 fluid
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07-27-2020, 11:13 AM | #8 |
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Without an LSD I'd be surprised if it got above 100C, as there aren't any clutch plates to heat up, just the relatively low frictional losses from the gears meshing. In normal use the diff will only be at 50 or 60C in 30C ambients. Difficult to tell what oil to use without a temperature reading immediately after coming off the track, then add 10C or so to allow for the cool down lap before the exit.
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07-27-2020, 11:48 AM | #9 |
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Same for a geared LSD like the Wavetrac?
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08-08-2020, 09:50 PM | #11 | |
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