4 replies [Last post]
barlow53
barlow53's picture
 Offline
VBMWMO #9125
Joined: 07/08/2016
Posts: 24

The original BMW Owner's Manual states that the pre-70's Twins should consume 32 oz. to 48 oz. per 1000 miles of travel or calculated to be 1 oz. per 31 miles or 1 oz. per 21 miles. Does this seem correct to you based on your experience with your motorcycle(s)? This is assumes that your engine is in good condition and not worn out with high mileage.

It seems all types of boxer engines tend to consume oil (original VW bugs, Porsches, Subarus. etc.) as is due to this type of engine configuration.....

Thanks for your replies!

schrader7032
schrader7032's picture
 Offline
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6885
Well things did get better in

Well things did get better in the /5-on era where the typical oil consumption was more like 2000-2500 miles per quart. I think it comes down to a better design. The system for relieve the internal air pressure due to the cylinders approaching bottom dead center at the same time was greatly improved. This system on the /2 era bikes is a series of circular passageways which "magically" align at certain points in the engine rotation to allow the pressure to escape. In the /5-on era bikes, there was a hole in the top of the engine with a spring loaded disk being held down until the pressure got to a certain point, and then it would relieve the pressure through a pathway to one or more carbs. On some of these bikes, the air and oil mist that was pushed out went through a channel where that mist was slowed down and the oil was allowed to settle out and small amount of oil would drip back into the crankcase.

Maybe better rings in the newer design? Tighter tolerances? Might be a variety of reasons.

__________________

Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

312Icarus
312Icarus's picture
 Online
Joined: 07/15/2016
Posts: 435
I don’t know...I’ve owned

I don’t know...I’ve owned dozens of air cooled boxer vehicles over the years from dozens of bugs, busses, from ‘58-76 following the arc of evolution, into the water cooled Vangon Syncros. Plus a trio of Porsches from a 912E (4 cyl) to a couple of 911 6 cyl as well as a handful of Subarus, and none of them use significant oil. My /2 doesn’t use any appreciable oil between changes. Granted, I don’t drive it at redline all the tine.

Curiously, my current ‘16 Subaru Outback is the worst, but only if I drive it faster than 75 mph consistently. Driving cross country with 75-85mph limits in ND/MT all of a sudden it uses oil.

A good tight engine doesn’t use much oil. The manual for most vehicles is written to protect the manufacturer when people complain about oil usage IMHO.

Icarus

miller6997
miller6997's picture
 Offline
VBMWMO #6997
Joined: 10/27/2006
Posts: 1101
Not even close!

32 to 48 ounces consumed per 1000 miles? Never. That's nearly half the capacity! My '67, in the family since new, uses very little between thousand-mile changes. On every ride of any length it weeps around the rear seal into the little ledge on the back of the engine. If I'm lazy and don't wipe that out after every ride, it may accumulate an ounce or so. Occasionally I'll need to top up the sump with maybe half a cup. I keep an eye on it, but I would never think of it as an oil-burner or oil dripper. My long ago departed Norton Atlas, on the other hand....

__________________

Jon Miller
'67 R69S
'13 F800GT
Altadena, California

Grant R26
Grant R26's picture
 Offline
VBMWMO #8145
Toronto Canada and Long Island, Nova Scotia
Joined: 03/28/2011
Posts: 208
Hello Barlow I'm certainly no

Hello Barlow
I'm certainly no expert but I have a R51/, a R/60 and an R27 and drive them daily to work here in the city and go for long rides....put several thousand on all of them each year.

All of these plus a couple of R26 bikes I've owned have a similar quirk...the first quarter liter on the dip stick disappeared in the first hour or two of driving. Then, consumption really levels off. Years ago I was always careful to top them up daily and if memory serves I probably burned through a liter (quart) in 1000 miles. (as per the specs in the original manuals)

Later on, I started to let it drop a bit and topped it up once it got noticeably below the 1-3/4 liter line on the stick...but never letting it get close to the 1-1/2 line. then my consumption dropped dramatically.

That said, it is ideal to maximize the volume of oil available to cool the engine. So I've been gradually converting all my bikes over to the oversized sump. I never liked the non original appearance but I've gotten over that; now when my stick reads 1-3/4 I actually have well well over two liters still in the sump.

if your bike is not smoking and not fouling the plugs then just enjoy riding the bike and add oil as needed. The cheapest part of owning an old bike is the oil (grin)

Compared to my '51 Norton, 1 liter of oil used in 1000 miles is unheard of !! Just be sure to change the oil often and use a high zinc content oil.

Grant in Toronto

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.