Gear oil for '98 K1200RS trans and final drive

goneregret · Apr 18, 2018

Hello all. I have a 1998 K1200RS with 50,000 miles and I'm trying to decide what gear oil to put in the transmission and final drive. A youtube video recommended Castrol MTX SAE 75W-140 but I can't find that for sale anywhere. My local BMW bike service department recommended 75W-90 but didn't have a brand name for me. BMW has the 75W-90 with their own brand name on it for $22 a liter and I'll need two bottles. Can anyone recommend a type of oil and brand name? I use the bike for commuting, canyon riding, and some long distance touring. I'd like to do this on the cheap if I can but prefer to use good products. Thanks for any help.

roncooper · Apr 18, 2018

Castrol 80-90 is what I use in my K75. I don't believe the 75-140 oil is specified for your final drive. Do you have a owner's manual to check?

pglaves · Apr 18, 2018

DO NOT use the 75W140 oil in the final drive. It is out of spec and can contribute to damage or failure. It is allowed in the transmission.

The specification for the final drive is 90wt GL5 rated gear oil. 80w90 is an acceptable substitute. Castrol brand "Limited Slip" in 80W90 wt is what I use and would recommend.

AntonLargiader · Apr 18, 2018

You won't go wrong with Mobil 1 75W90 or any name brand 75W90 or 80W90.

goneregret · Apr 18, 2018

Thanks for the help everyone. Unfortunately I don't have an owners manual. I have a repair manual but it only says "Brand-name hypoid gear oil, SAE 90, API class GL 5." Unfortunately I don't understand what that means.

I found the Castrol Limited Slip 80W-90.

https://www.amazon.com/Castrol-Axle...8-1-fkmr1&keywords=castrol+limited+slip+80w90

That's it on amazon but the local O'reiley's has it for half that price. I'll buy it there.

Just to be sure, I fill the final drive and the transmission up until the oil reaches the filler hole threads, right?
And, the transmission drain plug doesn't have a washer, right?
And, that transmission drain plug requires a 14mm hex head, right?

AntonLargiader · Apr 18, 2018

Yes, yes, yes.

T-foiler · Apr 18, 2018

I think it’s no, no, and yes.
180ml in rear-end and fill hole threads in tranny
Crush washer in tranny plug?

pglaves · Apr 18, 2018

T-foiler said:
I think it’s no, no, and yes.
180ml in rear-end and fill hole threads in tranny
Crush washer in tranny plug?

Different model. He has a 1998 K1200RS - flop-four engine, etc - in other words a "Brick K1200". Fill to threads on both final drive and transmission.

myK1200rs · Apr 19, 2018

PGlaves said:
Different model. He has a 1998 K1200RS - flop-four engine, etc - in other words a "Brick K1200". Fill to threads on both final drive and transmission.

AND... assuming his K1200RS is on a flat level surface AND on center-stand when measuring to bottom of side hole (transmission) or bottom of thread on final drive fill plug.

Paul and others.... I know it sound obvious to you (and to me), BUT I have seen many assumptions go wrong, hence I would rather repeat it and go on the "safe" side. EVEN MORE SO, when I see a poster like this gentlemen here that say he does not understand what his owner's manual is referring to with GL5 certified gear oil.

goneregret · Apr 21, 2018

Thanks for the help everyone. I just finished the oil change. Went very well considering there are always many snags to work out when doing anything on a new type of bike.

I did put the bike on the center stand. The ground is not quite level so I used a bubble level and strips of dense rubber to level it out. I held the level on the ground, on the feet of the center stand, and set it across the gas tank cap. I couldn't figure out a better way to level it unless I called in a surveying crew

One last question, what is the oil change interval on the transmission? The final drive calls for every 24,000 miles. Is it the same for the transmission?

PS, I paid my tuition in college by fixing old airheads. I'm not new to BMWs, but this is my first K bike and by far the newest vehicle I have every owned. Also the first one that's red :dance

98lee · Apr 21, 2018

I just want to highlight to any non K1200 brick owners (K75, K100, K1100, and K1) who are reading this thread. While you do fill your final drive to the bottom of the filler threads, DO NOT fill your transmission to the threads.

The K75s and two valve K100s use the factory shock spanner handle as a dipstick. There is a fill to line on the bottom 1/2" of the handle. The K1100s and I believe the 4 valve K100s and K1s have a bent sheet metal dipstick in the tool kit. If you don't have the tool, make one with the fill to line 4 9/16" (116mm) below the top lip of the filler hole.

I hopes this will avert any confusion.

:dance

pglaves · Apr 21, 2018

98lee said:
I just want to highlight to any non K1200 brick owners (K75, K100, K1100, and K1) who are reading this thread. While you do fill your final drive to the bottom of the filler threads, DO NOT fill your transmission to the threads.

The K75s and two valve K100s use the factory shock spanner handle as a dipstick. There is a fill to line on the bottom 1/2" of the handle. The K1100s and I believe the 4 valve K100s and K1s have a bent sheet metal dipstick in the tool kit. If you don't have the tool, make one with the fill to line 4 9/16" below the top lip of the filler hole.

I hopes this will avert any confusion.

Thanks Lee. I'll add that on the K75 and 2 valve K100 5 speeds the fill takes 850cc. I'm not sure on the 4 valve and K1100 bikes. I measure the 850ccs and pour it in. Then I verify by using the dipstick/shock wrench.

98lee · Apr 21, 2018

PGlaves said:
Thanks Lee. I'll add that on the K75 and 2 valve K100 5 speeds the fill takes 850cc. I'm not sure on the 4 valve and K1100 bikes.

Yep, .85liters or 1.8 pints.

. But if your just checking and not changing, you NEED a dipstick.

4valve (except the K12) bikes are the same.

:dance

pglaves · Apr 22, 2018

98lee said:
Yep, .85liters or 1.8 pints.. But if your just checking and not changing, you NEED a dipstick.

4valve (except the K12) bikes are the same.

There are a whole lot of things in life that need a dipstick.

My point was that when changing the oil, it is a pain to pour in some, check with the dipstick; pour more in; repeat. Much easier to pour in 850cc and verify with the dipstick.

Omega Man · Apr 22, 2018

98lee said:
Yep, .85liters or 1.8 pints.. But if your just checking and not changing, you NEED a dipstick.

4valve (except the K12) bikes are the same.

It would be interesting to see a picture of that dipstick wench deal.
OM

goneregret · Apr 22, 2018

All great information, glad to know my 1998 K1200RS is the easy one and I just fill it to the threads.

What is the oil change interval on the transmission? My repair manual says the oil change interval on the final drive is 24,000 miles. What is it on the transmission?

Thanks again!

pglaves · Apr 22, 2018

Omega Man said:
It would be interesting to see a picture of that dipstick wench deal.
OM

It is a typical hook wrench to adjust the preload on an OEM shock. Insert the handle end straight down the fill hole. The line scribed near the tip is the "full" mark.

Omega Man · Apr 22, 2018

PGlaves said:
It is a typical hook wrench to adjust the preload on an OEM shock. Insert the handle end straight down the fill hole. The line scribed near the tip is the "full" mark.

Thanks. I was hoping for something a little more precise

I take it that it is a ”bottom-up” measure?
OM

pglaves · Apr 22, 2018

Omega Man said:
Thanks. I was hoping for something a little more precise I take it that it is a ”bottom-up” measure?
OM

The handle goes straight down, hanging in the fill hole resting on the flat by the start of the hook. The tip reaches down into the oil when there is enough oil, and the proper "level" of the top of the oil coincides with the line on the wrench handle. It works just like any other dipstick extending down into the lubricant. Bike upright and more or less level on the centerstand of course.

As Lee mentioned, the distance from the flat by the hook to the "full" line is 116mm. That is, the transmission is full when the top of the oil is 116mm below the top edge of the fill hole. (Bike upright and level and all that common sense stuff.)

Omega Man · Apr 22, 2018

PGlaves said:
The handle goes straight down, hanging in the fill hole resting on the flat by the start of the hook. The tip reaches down into the oil when there is enough oil, and the proper "level" of the top of the oil coincides with the line on the wrench handle. It works just like any other dipstick extending down into the lubricant.

Great

First time I have seen this on the forum. I have a feeling it will help many with this style final drive.
I like oil......I like checking oil (lube)......I’m still :scratch

on the new cars with no dipstick :gerg

OM

Gear oil for '98 K1200RS trans and final drive

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