Transmission oil change on a Rex from 2016 onwards

Pipino said:

The valvomax is a smart litte device, but in this case not suitable to my opinion.
- It looks like the valvomax is made from stainless steel, not recommendable to use on aluminium surfaces like the BMW i3 gear box.
- it is missing the magnet for collecting any metal parts
- it seems too bulky to not interfere with the heat protection on the rex.

In May '23 I drained the gear oil and replaced the original plug (M16x1.5) with a galvanised plug with normal hex head (so can be tightened/loosened with spanner). A 0.8 mm hole was drilled through the plug and M5 standard thread with 90 degree angle to support a small hose tail and later a small modified cone point grub screw (hardness 12.9) to plug it off. A small but strong O-shaped magnet was attached to the new plug-end to catch any additional metal coming from the gear box. I used an aluminium washer and tightened it with a torque somewhat higher than the set value by BMW: the new aluminium washer had a larger total surface than the original one. Oil I used was 500 ml GL5 rated SAE 70W-80 from BMW via getbmwparts. This is the same amount I got out of the gear box. The oil went in under gravity (1 m), but it took some time (45 min - 1 h). After removing the hose tail NO oil came out, but nevertheless had everything prepared to inserted the cone grub screw with loctite threadlocker stick 37643 so I did it quickly.
Checked after 1 month and found no issues. Driving now for almost 10 months without problems and average mi/kWh went up. Can not prove it was due to the oil change, but logic says that it does help to get things running smoother.

I was thinking to make more of these modified plugs if there would be interest in them.

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nilknarf said:

I love Pinpino's solution and following his lead, I discovered that an M16 oil pressure sensor adapter will fit. The adapter accepts a 1/8" NPT male plug, so you can use a 1/8" NPT magnetic drain plug made for motorcycles. I also picked up a 1/8" thread to 3/8" barbed hose adapter to use as the fill adapter. The fill adapter swivels so that I don't have to worry about the stationary hose when I'm unscrewing the other end of the adapter.

Pipino's plug is still just as viable a solution and I believe that his drain plug is stronger than the oil pressure adapter. As he was still contemplating producing more, I thought I would post this as another option, but am hoping that he can ramp up production for the group.

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Pipino said:

The valvomax is a smart litte device, but in this case not suitable to my opinion.
- It looks like the valvomax is made from stainless steel, not recommendable to use on aluminium surfaces like the BMW i3 gear box.
- it is missing the magnet for collecting any metal parts
- it seems too bulky to not interfere with the heat protection on the rex.

In May '23 I drained the gear oil and replaced the original plug (M16x1.5) with a galvanised plug with normal hex head (so can be tightened/loosened with spanner). A 0.8 mm hole was drilled through the plug and M5 standard thread with 90 degree angle to support a small hose tail and later a small modified cone point grub screw (hardness 12.9) to plug it off. A small but strong O-shaped magnet was attached to the new plug-end to catch any additional metal coming from the gear box. I used an aluminium washer and tightened it with a torque somewhat higher than the set value by BMW: the new aluminium washer had a larger total surface than the original one. Oil I used was 500 ml GL5 rated SAE 70W-80 from BMW via getbmwparts. This is the same amount I got out of the gear box. The oil went in under gravity (1 m), but it took some time (45 min - 1 h). After removing the hose tail NO oil came out, but nevertheless had everything prepared to inserted the cone grub screw with loctite threadlocker stick 37643 so I did it quickly.
Checked after 1 month and found no issues. Driving now for almost 10 months without problems and average mi/kWh went up. Can not prove it was due to the oil change, but logic says that it does help to get things running smoother.

I was thinking to make more of these modified plugs if there would be interest in them.

Click to expand...

• Oil Pressure Sensor Adapter $10.99 at Amazon or $3.27 at Aliexpress There are also cheaper ones made of aluminum, but I went with stainless steel as I would be afraid of breaking an aluminum one when torquing. Stainless steel should be safe in this application as there is no electrolyte present to enable galvanic corrosion.​

• Oil drain plug: $9.99 + $5.00 shipping at Prism Motorcycles These can also be found for around the same price on eBay. Just search for 1/8 NPT magnetic plug or you can search the Harley Davidson part number of 739a.​

• Hose fitting: $10.99 at Amazon

nilknarf said:

• Oil Pressure Sensor Adapter $10.99 at Amazon or $3.27 at Aliexpress There are also cheaper ones made of aluminum, but I went with stainless steel as I would be afraid of breaking an aluminum one when torquing. Stainless steel should be safe in this application as there is no electrolyte present to enable galvanic corrosion.​

• Oil drain plug: $9.99 + $5.00 shipping at Prism Motorcycles These can also be found for around the same price on eBay. Just search for 1/8 NPT magnetic plug or you can search the Harley Davidson part number of 739a.​

• Hose fitting: $10.99 at Amazon

Click to expand...

Pipino said:

I found there were a couple of issues to be tackled:
- prevent oil spillage as much as possible : small hole 0.8 - 1.0 mm
- overcome the limited space because of heat shield : grub screw flush with head of plug
- keep magnet to collect any metal shavings: requires a strong magnet with a hole
- have the hole closed off properly (you don't want to have oil leaking from the gearbox after x amount of miles) : install a m5 hardened modified grub screw with 90 degree head in the plug which has the 90 degree counter form (used a special 90 degree drill to make this).

I can produce more of these plugs.
Can include the hose and tails to connect to the oil bottle cap, so you're all set except for the 500ml oil and loctite.

Send me a message if you're interested.

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