I've recently purchased an '85 BMW and am replacing my fluids for the coming summer. 

While this may seem like a very rookie request for advice in a room of enthusiasts - I'm wondering what exactly I should be purchasing.

I'm guessing a good semi-synthetic 30 / 50 for the engine is appropriate, but what should I be using for the gear box and final drive? Also as it's my first liquid cooled motorcycle, what kind of coolant should I buy and I imagine I should mix with distilled water but at what ratio?

Also any tips on things I should watch for or do while doing maintenance? (I read in here a thread which recommended pulling off the cover of the water pump and checking the impeller - any other tips?)

Anyone who has the patience to give me a few tips I would highly appreciate  Cheers and safe riding!

nothing wrong with mineral oils ...yes 20 -50 is a good start
a ryco 412 oil filter is cheap and easy to find around here  (there maybe better )
standard differential oil 80-90 for gearbox and diff (bevel drive ) about 1.25 litres

choose a good reputation fluid for cooling system

but plan to replace all rubber on the fuel lines ,Inside and out of the tank...whilst there flush the tank out  before going anywhere , including the pump and suspension rubber mount stuff

,,theres a telltale hole from the water -oil pump at the front of the sump  about 4-5mm in size ..park the bike over a sheet of newspaper ,, after you get a start happening and more than a few kilometers travelled ...to check for leakage of either oil or water ...

make sure the battery is no older than 3 years ...if its been sitting

and please be careful on old tyres

cheers

Great thank you Charlie. I've put a new battery and new tyres on the bike. The old fluids weren't looking horrible so I gently put a few hundred km's on it already and it doesn't leek a drop! 

I'll check over the fuel lines, hoping to get through the season as is and pull the tank off for a major service / paint job in the fall. Luckily the bike hasn't sat for more than 6 months in a stretch and the previous owners (two brothers who bought her new in '85) took great care it. 

I don't see any c-clips holding the tank in the brackets and no bolts however I've given it a couple good pulls and it doesn't move much. Am I missing something or should I just pull harder?

85 there was a change in the tank, early ones tank was bolted with a single bolt at the rear of the tank. Later ones are clipped. Or should be. The clips often get lost and then the tank can be lifted at the rear but the pins go through two rubbers that can be stiff so a little levering is needed.

Lift rear of tank and pull it back, but before doing either disconnect the electrical plug, front left or rear right, just pulls out. Disconnect the two fuel lines but be careful as it is possible to break the aluminium spigots. when you are cutting the new fuel lines make them about 1 1/2" longer and you will be able to access radiator cap and electrical relay box without disconnecting the fuel lines.

As for oil, I have just put fully synthetic 5W40 in the 84 K100RT and the 97 K1100LT, next change will be April. They get good use, even in winter.

hmm 85 model ...could be that the tank is fixed to the frame at the back ?  just lift the seat to check
but if its a later version like mine ..could have early and late bits ....the later tanks as you say  hold in by two posts from the tank through frame mounted grommets ....the trick is to put pressure at the back of the tank and push forward ..then lift ... I don't think iv seen an aussie version with the clips actually fitted to the tank posts  ...grin ..

olaf is right about the oils ..but out here for many of us , it really doesn't get that cold ...except maybe a few weeks a year ...unless you live at some altitude, to demand the 5 weight oil 
but we all have different experiences  and common practices for our environments

good to hear about the battery and tyres 

charlie99 wrote:
a ryco 412 oil filter is cheap and easy to find around here

It's a Ryco 418 mate. Not sure what a 412 is for but probably a Mack or Kenworth

RicK G wrote:

charlie99 wrote:
a ryco 412 oil filter is cheap and easy to find around here

It's a Ryco 418 mate. Not sure what a 412 is for but probably a Mack or Kenworth

sheesh ..bloody memory left me for a moment ...thanks rick  the 412 is actually a fuel filter ,,,sorry

the riddle was ( 4 ) cylinders ( 1 ) thousand cc ( 8 ) valves ......bangs head on bench ....grin

kevinryu wrote:....
I'm guessing a good semi-synthetic 30 / 50 for the engine is appropriate, but what should I be using for the gear box and final drive? Also as it's my first liquid cooled motorcycle, what kind of coolant should I buy and I imagine I should mix with distilled water but at what ratio?

Also any tips on things I should watch for or do while doing maintenance? (I read in here a thread which recommended pulling off the cover of the water pump and checking the impeller - any other tips?)

Climate and ambient temps you're riding in will determine engine oil grades. In Australia 20w50 is best. 10w40 is more suited to colder climates. I use 15w50 synthetic in all my machines but its a matter of choice. Mineral is fine. If your machine has been running on mineral and you switch to synthetic, you run the risk of disturbing the status quo of seals and joints etc as synth is more detergent and will remove gunge that has built up around old sealing surfaces creating leaks.

Any coolant is suitable for alloy engines these days. Just mix it according to instructions on the bottle. Coolant's main action is to act as an anti-freeze. This is generally not a problem in AU. It has minimal effect raising the boiling point, so higher than specified concentration is pointless. I use Tectaloy Long Life available in K-Mart and other auto retailers. The system doesn't take much. I just buy demineralised ironing water from the supermarket for a couple of bucks.

I don't think there is any reason to pull the cover off the water/oil pump. If there is an issue with the pump it needs to be removed for an overhaul.

Congrats on your purchase. Enjoy the ride.

While you might consider using 1980s technology 20/50 mineral oil, you perhaps should also use 1980s tyres that are rubbish compared with modern rubber. 
Or there again, you could use modern 5/40 synthetic oil which will lubricate much better and modern tyres which work better too.

Despite the zillions of internet oil threads regarding every type of motor on the planet, the most important thing for any motor is to change it at required intervals.

K bikes are "bulletproof" and I have never heard of a K engine failing due to oil issues. (I often joke that K bikes could run on vegetable oil.)

I occasionally run "high mileage" labeled oil through my bikes as those have additives to help keep seals in good shape. (Like the clutch nut O-ring and rear seal on a K.)

K bikes do consume oil so it is important to check/top off the oil level regularly and do not worry if your bike consumes oil.  People will often say that model/year XXX/YYY should burn X amount of oil but having owned something like 20 or more of them in my experience it just varies from bike to bike.

75-140 gear oil works well in the transmission and K bikes shift better if you use a gear oil with moly additives or add your own moly.

Any coolant safe for aluminum (they pretty much all are these days) is fine.  Be sure to use DISTILLED water in the cooling system. 60 water/40 coolant is fine.

Think of a K bike as a car on two wheels.

+1 on just about any coolant commercially available being suitable, subject to being mixed according to directions on the container for the expected temperature conditions.

I would also add that a big part of the reason for using such coolant is the resistance to corrosion, especially where there are dissimilar metals involved. Many of us who've been around longer will remember the coolant in car engines (bikes were just about all air cooled) usually being the colour of the rust that was being carried through the system and coating the insides.
If you look at any engine that has been properly maintained and had it's coolant changed regularly, you will often see that the coolant is the same colour as it went in, and the insides don't look much different to when it came out of the factory.

Which emphasises the other point - change it regularly according to BMW and coolant manufacturer recommendation.

Bill

Coolants are much better these days with better anti-corrosion additives so a lot of them now are supposedly good for five years.

The recommended service interval by BMW is two years.  Given the effort required and cost (low) that's probably a good schedule to follow though.

The OEM coolant is not that dear, but as stated use distilled water.
Regards Martin.

M
Hello!

Use the right cooland liquid.
Glysantin Alu-Protect G30, G12+ (=G30), G12++ (=G40), G13 = GG40
Should be red Silicat free.
I use G48 but G30 is OK.


Cheers


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