Oil coolers..why on some models and not others?

[moosehead]

Just a curiosity question.

77 R100RS - no oil cooler
82 R100RS - oil cooler
81 R100 - no oil cooler

Was the oil cooler an option on bikes when first purchased? Did any of the early RS's (76, 77, 78) come standard with oil cooler or was it an option. My 77 has no oil cooler but the 82 does? Why no cooler on the 81 R100 or was that an option also.
What is the reason for the oil cooler on some models and not on others?

[ME 109]

All I can think is 'cause they felt like it'................... and they didn't felt like it.
I have an oil cooler that.........didn't felt like it.

[Garnet]

Oil coolers first appeared in 1978 as standard equipment on the RS. I believe they where standard on the RT when it first came out, but don't quote me on that.

After that they sorta came and went as the Unterfuhrers at BMW whims changed.

[Garnet]

Sorry, I just actually read your question.

Initally it was just the full fairing bikes that had oil coolers. The fairing bikes had thermostats on the coolers. At some piont the GSs got coolers, but without the thermos.

It's odd when you think about it, the fairing bikes where already a PITA to change oil filters, sooooo they put a big lump of a theromstat in the way to make it even tougher. The GSs where easier to get at but there was no thermo.

Unless you had a PD. Then there's that bash plate.......... where the hell is GSPD??????????????

[moosehead]

So Garnet, none of the fully faired early RS's (76,77) had an oil cooler but beginning in 78 all faired bikes (RS, RT etc) came with one? Or what ever the engineers thought back in those days. As I noted my 77RS has no cooler and don't plan on adding one either. You helped answer my curiosity.

Yea that thermostat oil filter cover was a pain in the ass in doing oil changes. Took mine off my 82 RS and replaced with flat one same as the GS's. Made life easier at oil filter change time. The orig t'stat cover split one time on install so just chucked it.

I can see with full faired bike that it would make some sense with oil cooler. My GS had the oil cooler but I didn't have the thermostat type oil filter cover, just plain flat one. I moved it up under the headstock eit shoulda been in the first place! It was a disaster waiting to happen sitting out there on the engine guard. Had a oil temp guage on my old GS and surprisingly that oil cooler actually did have impact on lowerewing oil temps. When I busted one of the lines I ran it for a few months in the hot weather and the temps consistantly ran 10-20C hotter. When rebooted the oil cooler it did impact oil temps especially at hwy speeds. Use to cover it up in the cold days. Guess if there was a thermostat at the oil filter cover it would be doing its job in cooler weather.

[vanzen]

Heat will be THE nemesis of both oil and engine.
Airhead engines are designed to operate within a certain specific range of temperature.
Depending upon your riding / environmental circumstances –
and a full fairing (RS or RT –think about the restriction of air-flow)
plays a significant part in this decision ...
An oil cooler just may be cheap insurance to guarantee engine longevity
by keeping the engine within this range of operating temperature.
My guess will be that the factory did not arbitrarily add this feature
and that the addition might be the result of considerable research ...

Folks will like to whine about the thermostat.
Again "specific range of temperature"
and engines operating with cold oil = X wear and tear on the engine.

Do you need an oil cooler ?
Circumstances will prevail, your choice, eh ?

[dougie]

I considered removing mine, but after observing that it does its job, decided to keep it.

[ME 109]

A thermostat is not much use at all.....if it doesn't work.
The way to check if it is working, is to feel the radiator on a hot day.
If the radiator is only air temp, it means the thermostat is not functioning.......or the engine oil is not hot enough for the thermostat to open.
In my own experience, feeling the radiator one blistering day proved it to be only air temp. If it wasn't going to work then, when the hell was it going to work??

The part which actuates the thermostat piston is called an 'expanding element' which is a wax filled brass? cartridge with a metal pin that pushes out when the wax heats sufficiently.
I can only assume my expanding element doesn't work (not that one!)

[dougie]

Bound to happen when you get old Jeff.

[ME 109]

Oi! where did yer post go Vanzen?

My point stating the obvious is to do with all the talk past and present, about oil coolers.
Which amounts to nothing, if the thermostat doesn't work.
Which is part of the discussion that never really gets consideration.