OLD MAN SLINGER RANT!!

[Tinkertimejeff]

Another thing I found with the "Barn Bike" (Turf Green) the left side wrist pin bushing was scorched and had worked it's way about halfway out of the connecting rod bore. That indicates to me that it had heated up due to a lack of oil.

[cwf]

It's not just the bikes or the oil that has changed. Back then, 60s, 70s, 80s, we were young, bikes were plentiful and relatively cheap: if it broke, a friend of a friend could fix it or there was always another somewhere.

Now, after a lifetime of learning the right/hard way, we are necessarily more careful. The same bikes are much more expensive, so we're more careful. We have families, bad backs, responsibilities, none of which fit on a bike, so they are more of a valuable heirloom.

But, a bit of sun and a twisty road and they're still fun.

Charlie.

[xackley]

68k on my R69. Same performance, compression, and sound as when I bought it in 1977 with 12k on the odo. Never an issue, with the the exception of the rivets giving way on the clutch plate.
Back in the 70s and 80s every one was predicting doom from unleaded gas eating the valves and seats. I ignored that and still have loads of adjustment available.

Then, with the internet, came pictures claiming disaster caused by the slinger, from engines that obviously were long over due for an oil change.

These are hand built engines, assembled by experts. My opinion is don't mess with perfection without good cause.

And does anyone still put thousands of miles on their old bmw every year? Tearing down the engine for a future that is never going to happen seems like a dangerous gamble.

Don

[niall4473]

The detergent in the oil is to stop the small particles of solids flocculating, so that they will stay in suspension until caught in the very effective filters which modern engines have, so naturally when those agents encounter aggregates of sludge, they will set about dissolving them.
Old, straight oils did not include such additives so the strategy was to centrifuge the aggregates out or settle them in the sump or oil tank.
I don't think that pre-1969 BMWs are any more vulnerable to this than other old bikes, in fact probably less so than most.
So in answer to the question "How can detergent oil cause the rock-hard slinger deposits to go into suspension?":- well, it is highly unlikely that it will, any lumps of aggregated sludge doing the rounds will probably have come from somewhere else, but of course, a heavily impacted and full thrower trap will not catch it before it sticks in some bottleneck.
I have stripped a few Nortons where the hollow crankshaft was absolutely chock full of solid sludge and it had also built up around the rocker gear, but the engines had suffered no harm, but by contrast my cousin bought a time capsule BSA Road Rocket which had been in a lock-up since 1968 and it went less than 100 miles before a monumental blow destroyed the engine, and the remains were remarkably clear of sludge when I stripped them.

[Slash2rider]

How clean/ dirty oil pan should be? Here is mine 1500 miles of thrashing most two up,love the scream it makes at 7000rpm. Oil bit dark in colour as carbs are set on the rich side.

[TaosTwinCam]

I'm going to stick my neck out and venture an opinion. I believe that most of the trash found in your slingers happens in the first 500 or 600 miles with a fresh motor. Back in the early 90s I rebuilt a Harley motor. All new quality parts, professional machine work, scrupulously clean. A friend called just before startup and advised that I remove the return line to the oil tank and puke the first pint of oil into a coffee can. To my surprise, I found a full teaspoon of metallic trash in the bottom of that coffee can. Same deal with any fresh motor. Fresh crankshaft, new bearings and bushings, cam and tappets, timing gears, rings scaping the cylinder walls. Everything sheds metal during break in. Ever notice how a rebuilt BMW motor smooths out around 500 miles? It's broke in. All the parts have smoothed out and gotten used to working together. Internal friction goes way down and the motor gets happy. So all that shed metal is trapped in your slingers. In the perfect world , we would break our fresh motors down at around 1500 miles and clean the slingers. Then keep your oil clean. What collects after that is mostly combustion soot that sneaks by the rings over time. A much slower process. In changing oil on my own bikes, I hardly ever find trash on the magnetic drain plugs. I believe that the Old Man is correct. If you have an old bike that runs well and doesn't shed metal, Keep the oil clean and ride it in confidence. Another Old Man....Todd

[R68]

I've had exactly the same experience: a new rebuilt motor must shed some metal parts, the first oil change shows some silver "sheen"...it important to do first oil change early, maybe 100 miles or so?

[VintageJim]

In 1974 before I drove my 1966 R60 across Canada, Karl's BMW in Minneapolis suggested I get the slinger cleaned on the bike with about 25K miles. At that time I had little money and no idea what the mechanic was talking about and drove the bike across Canada to Vancouver and back through the US. I sold the bike when it had about 35k miles and it never did have a crank problem.

[schrader7032]

When I broke in my R69S, I changed oil after the first ride of 25 miles. Noticed a fair amount of silvery flakes in the oil. I changed oil again at 200 miles, still saw some flakes but less. Changed oil at 500 miles and noted that there was nothing unusual floating in the oil. I then went to regular intervals like 1K-2K miles or every 12-18 months.

[sherman980]

Todd,
LOL!!! When did we get to be "Old Men"?!! Last I looked I was still in my 30's!!

Todd/R68,
Definitely on target. I rarely let a new motor go more than 50 miles before the first oil change. Again at 100 miles or so, 500 miles and every 1000 thereafter...

Also, hate to start another controversy/oil thread, but... for my old rides with less than perfect history, I make sure to run non-detergent oil in them. No need to "wash" all the built up crud on the crankcase walls, etc. into the oil and then into the rest of the motor. On new builds that I know are clean from the start, I typically run a high grade detergent oil as I'm not worried about "loosening" old crud. Not sure if there is any actual science behind this but it makes me "feel" good.