Oil Cooler

[Adrian]

Hi again. As the rebuild progresses I am thinking about keeping the engine cooler than it has been in the summer months ~ especially as I intend to tour around Oz a fair bit once it's all finished. My bike is a 1984 R 65.
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 I am thinking of two ways to go on this. Either an extension to the sump or using an oil cooler. I have seen an Israeli firm advertise an extension which also includes an external oil filter.
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 Any advice people ~ thanks ..... Adrian

[Tony Smith]

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 I am thinking of two ways to go on this. Either an extension to the sump or using an oil cooler. I have seen an Israeli firm advertise an extension which also includes an external oil filter.
 .
 Any advice people ~ thanks ..... Adrian

Once upon a time, say in the late 70s to early 80s I would have routinely said that the BMW boxer needed an oil cooler and greater sump capacity - but then I would have been talking about my 1978 R100RS which is essentially a /7 in wolf's clothing.

I managed to scare myself a couple of times with engine temperature problems and at one stage bought a complete oil cooler kit from a later model to fit, but sometime in the early 80s the problem went away, at least as far as oil behaving strangely when it got hot. The capacity problem remains unaddressed to this date - the sump on my R65 has a crack which I'd like to get welded up, so the plan is buy a new sump, put it in the R65 and get the old sump welded and then fit it to the R100.
 
The reason, by the way, why I never carried through the oil cooler fittment was that in the early 1980s  oil underwent a quantum level of improvement and suddenly the old "if it get to 120 degrees C its stuffed" mantra was no longer event remotely true.
 
I think I bored the group soem tiem back with the tale of my mate who rebuilt a Norton Atlas, rode it around for a year and then announced he was embarking on a near 6,500km trip on it. I bet money it wouldn't make it because no Atlas ever made went more than 3,000 miles without catastrophic failure due to the factory designed inadequate oiling system. But it made it in fine style - a simple endorsement that even ordinary "woolworths" oil in 1985 was better quality than the most expensive racing oil in 1967.
 
Similarly our old rubber cows.

Your R65 already has the biggest factory sump, there is no point in going bigger. A spin on filter has a small convenience factor over the factory arrangements, but at the asking price I could not be bothered.
 
I have a temperature dipstick on my R65, on occasion on a long run on a hot day, the temperate dips into the late 120's Celcius. I've stopped worrying - I run Penrite 20W/60 and change it at 6 month intervals regardless of miles (If I actually did 5,000 miles in 6 months I change it sooner, but I have just turned over 5,000 miles since it was rebuild and registered in November 2014, so I reckon I'm safe.

I digress - the first couple of oil changes after rebuild I sent away for analysis, partially to check that the thing was healthy and partially to check my oil improvement theory - in both cases the analysis came back that the oil was fine, and fit for further service with a suggested interval of another 6 months or 5,000km, whichever came first.

In other words what thwe lab was tellign me was that at my current useage patterns I could run the oil for 12 months and still be throwing away perfectly good oil.

The subtext  on that was that the occasional temperature excursions were not in any way affecting the oil.

Bottom line Adrian - use a good quality mineral oil and spend your money on something else, like maybe an R75 final drive or a 860cc kit.

[Adrian]

Thanks Tony - great story - using an oil cooler was just and idea - as you live in one of the hottest places in Oz its good to get your advice.
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By the way - where do I get a temperature dip stick .... Adrian

[Bob_Roller]

I got an oil temperature indicating dipstick in 1988 from a US aftermarket BMW parts company, Luftmeister .

I lived in the Chicago area at the time, it routinly gets to the mid 90's F, 35 C during the summer there .

I found that the oil temp was a lot higher than I though it would be, at 60 mph, around 100 kph in air temps of 95 F 38 C, the oil temp was 275 F, 135 C  .

After moving to Phoenix in 1993, the first summer here, average summer temp from mid May through mid October, is 105-107 F, 41-42C, but routinely gets to 46-49 C .

I saw oil temps of 350-375 F, 175-190 C at the same speed, 100 kph .

I questioned the accuracy of the indicator at that point .

I work for an airline in the aircraft maintenance department, a co-worker suggested using a piece of test equipment that measured the accuracy of thermocouples and thermo switches .

I tested the dipstick from 100 F, 38 C, through 450 F, 205 C and found the dipstick to be within 5-10 F, 2-5 C at the major graduation marks on the indicator face .

So the dipstick was not wildly inaccurate.

I got an OEM oil cooler kit from an after market parts supplier .

First thing I found out, was that the most costly part would not work on an R65, the thermostatic bypass valve that goes over the oil filter, won't clear the right exhaust pipe .

This was easily solved, by using a part from an airhead GS bike, the part that goes in place of the oil filter cover, does not have a bypass valve, just two banjo bolt ports .

The oil cooler dropped the oil temp by about 50 F, 28 C .

There's too much restriction in the banjo bolt, banjo hose fitting area to get a proper amount of oil to the cooler.

After going through this, I did not put a cooler on the '82 LS .

The national speed limit has been increased to 75 mph, 120 kph, so, I'm sure with this increase in speed, the oil temps are going to be back in an area where I would like to avoid .

So, I'm speed limited during the heat of the summer season here in the low deserts of central Aridzona on the airheads .

I would like to put one on, but not an OEM kit .

I would get an indication dipstick, just to see what kind of oil temps you have in your conditions during the summer .

I tried a full synthetic oil, but I got rear main seal leakage, so now I use a semi-synthetic oil .

Also, I don't know if this is the case for all aftermarket higher capacity/oil cooler sumps, but some render the center stand useless, you can't extend it past the sump .

Hope this helps you a bit in your decision .

Now, if I go out in the heat of the day, I use the oilhead, those bikes move a lot of oil through the two oil coolers .

[Barry]

Those are quite some oil temperatures especially when you consider that the oil in the bearings is maybe 30 Deg C hotter than the  sump temperature.

Not something I need worry about as the highest sump oil temperature I've ever measured is 80 Deg C. That's at the end of a ride using an thermocouple poked down the dipstick hole. I've no doubt it's higher at sustained high speed.

[Bob_Roller]

I've restricted my airhead use to early morning rides, 5 AM to 9 AM during the ' hot season ' on my days off. 8-)

The commute to work and back is at most 15 minutes on weekends and major hoildays, not a factor with the airheads .

[georgesgiralt]

IMHO, this is not a concern.
Given the number of bikes sold to the authorities (slow movement during parade and/or patrol) and given the mileage they have got (in France bikes with more than 200 000 km are not uncommon) I guess the oil did it's job and did it well.
Of course, in my 600 Honda, the oil is cooled with exchange with cold water from the very big radiator of the bike so temperature is I bet lower than on the BMW.
My R65 has done commuting since I bought it new be it winter or summer, and climate in south of France is very hot in summer and traffic jams are numerous. Every time I had to remove the sump or look at the pistons there where not so much burned oil. So I'm confident she will run fine for the foreseeable future...

[Adrian]

Thanks for the input guys - after Tony of Cairns wrote his story I've decided to not bother with one :-)