Dear All,

Yesterday I replaced the oil in the gear box. The old oil was a Nulon product, 80W-90W with all the appropriate specs. I replaced it with the same stuff. Only about 4000Km. When I first replaced it, the operation of the gear box improved quite dramatically, ie, easier shifting, no "klunkiness". Slowly noticed the shifting to become more "klunky". After replacing the oil, the operation of the gear box again became v.much easier.

I noticed this time that the drain plug was full of tiny slivers of metal, maybe 2-3mm long, v.fine, obviously from the verkinks of the innards of the gear box. Regrettably, I didn't take a pic. Are these slivers this normal? Is my gearbox wearing out before my eyes?

First of all: Having fine particles of metal at the magnetic drain plug for itself is NOTHING to worry about unless you're getting vast amounts of it (this accounts for the final drive as well)! You definitely have to start worrying when the fine metal is not fine anymore but actually little bits and pieces of several mm in diameter or if the amount is getting very/unusually high...

But if you have problems shifting or unusually loud noises, then there sure might be a problem, although for my taste BMW gear boxes seem to be very rough in the first place...

Have you been doing oil changes as indicated by service intervals? I do, not because of the oil turning bad (which it doesn't), but because I want to have a look at the plug and how the amount of metal and the 'chunk' size changes...
You might wanna take a picture of the metal on the drain plug for everyone to see and judge...

Hi Ulrich,
First off metal paste that accumulates on the magnetic drain plug which when rubbed between finger and thumb has no discernible texture is generally OK but slivers are bad - very bad and indicate something breaking up.

First and foremost I do not know about the quality of Nulon oil but Tom Cutter considered by many to be the guru on these gearboxes uses and recommends Castrol Hypoid oil only. I strongly suggest that you consider following his advice and seeing what results you get.
Regards,
K-BIKE

Yep, Castrol EPX (SAE 90)...

Be certain the oil you're using in the gearbox and the final drive is of the GL5 Hypoid variety. The viscosity isn't too terribly important unless it's 75W140 and you ride in Siberia. The factory (and most of us) recommend 75 to 90.

Wow! Thanx, lads. I've put about 15,000Km on it since I acquired it. I changed the oil when I first got it (@64,000Km) but don't recall the state of the drain plug (All excited!) This is the third change.

Will get the Castrol stuff, ensuring it has the GL5 spec and replace the Nulon stuff that's in there now. Planning a 1000Km ride this weekend, so it's a good opportunity to re-check the drain plug after the ride.

Also, I didn't "feel" the contents of the drain plug (between thumb and forefinger, but will do so.

Thanks again, Rick G.

Castrol Hypoy C is what Tom Cutter recommends, he also recommends against using Mobil 1 gear oil
Regards,
K-BIKE