K75SA Oil

I have had a '91 K75SA since November of 2003. It had 20,763 miles on it when I bought it, and now has 28,004. No trouble whatsoever. It is fully up to date on service, and I had the clutch splines lubed ahead of the specified miles due to the age of the bike.

I just got back from a ride to New Orleans and back (to New Hampshire): 3,560 miles.I did about half interstate (70+ mph) and half two lane (50 - 60 when not in towns). I noticed that I had used about 2/3ds to 3/4ths of a quart of oil. Is this in line with what others have experienced?

Also, the dealership will only recommend BMW oil, which I am using (synthetic), but I notice that the owners' manual does not even call for motorcycle specific oil. This makes sense to me, given the dry clutch. I looked at some other threads on this forum, and see people are using a variety of high quality non-motorcycle oils, but I didn't find anything specific to K75's. Any thoughts?

Thanks,

Dave Geyer
Merrimack, NH

Dave,

Don't worry about the oil consumption - it isn't very much. My experience (1988 K75S) was that it depended on how hard I twisted the throttle, not so much on what the cruising speed was.

Because it has a dry clutch and is liquid cooled, a K-bike's need for oil is just like a car's. Your dealer's recommendation of BMW-specific oil reflects BMWNA's preferences, but, as you've seen, many of us use and have used whatever sort of automotive oil, dyno or synth, pushes our buttons.

Jeff DiCarlo has written on some recent changes in oil formulations http://ibmwr.org/otech/oilreport.html

Thanks dbrick!

That link was great! Very informative.

Dave Geyer

My K75 has always weeped more oil than it burned. Even at well over 150,000 miles, it wasn't using enough to even notice a change in level on the sight glass.

I use regular old Castrol 20w50 from WalMart. The bike doesn't need anything more exotic than that.

jdiaz said:

I use regular old Castrol 20w50 from WalMart. The bike doesn't need anything more exotic than that.

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So, are you saying that you age your oil before you use it?

Dom't mind me, I'm just wasting time while my wife MOWS THE LAWN

HankB said:

So, are you saying that you age your oil before you use it?

Dom't mind me, I'm just wasting time while my wife MOWS THE LAWN

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I thought you were going on the club ride this weekend? My daughter and I showed up at the departure point to collect activity points.

jdiaz said:

I thought you were going on the club ride this weekend?

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Had to go to a wedding Saturday. We had hoped to join the group today and really tried. We had a bit of sun when we left at 7:30 but by the time we finished breakfast in Marengo, the rain had started. We braved the rain and distant thunder until we got into Wisconsin and checked the weather radar at the welcome center. It showed heavy rain from where we were to where we wanted to go. There was additional rain in the forecast and there were tornado warnings south of us. We decided to bag it and headed for home. I was much chagrined when the weather cleared, but now as the next line of T-storms rolls in, our decision to cut and run looks better. I hope the folks in La Crosse are getting better weather.

My daughter and I showed up at the departure point to collect activity points.

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So, was she in the top case? Or did you take your car? What do the rules say about riding an OTBMW?

HankB said:

So, was she in the top case? Or did you take your car? What do the rules say about riding an OTBMW?

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The rules allow everything. I didn't ride at all this weekend.....but the weather was perfect for doing a 36K service on my K12LT.

Every time I get an email telling me that someone has responded to my thread I get excited, thinking I'll get more information regarding the question I asked. Then I keep finding that it's just these two dudes having a conversation that they could carry on just as well via email.

Well I do thank you for the information! I can use all the help I can get!

Dave Geyer,
Merrimack, NH

oil

most oils are good for dry clutch bikes. If you don't plan on keeping it beyond 100k miles.

If you do, a synthetic is preferable. However, do not believe anyone who tells you to extend your oil change cycle when using synthetics.

Although synthetics sheer strength will last longer than organics, the multi-viscosity additives will not. In all oils i have tested, the oil has reverted to it's base viscosity after 3000 miles.

In other words, if you have 15-50W synthetic, in 3000 miles you have 15w oil. If it is 10-30W organic, 10W in 3k miles.

Synthetics are also very good for air-cooled biles due to it's high temperature stability.

I use mobile 1 15-50W for 3 reasons. High sheer strength for the cams, and high temp stability and low ash for the snail.

I use a simple rule in changing the oil. every time the odometer reads 3333, 6666, or 9999 on the last 4 integers, i change it.

oil

I always find it interesting when people talk about oil . Like, this is good, this not etc... ect... I own a small trucking Co. We.pay alot more att. to oil testing and how the samples were taken than just looking at it and saying it needs changing. Trans and rears too. All for under $ 10. per sample . Now I know trucks are some what different to bikes but if oil is dirty and broke down engine wear or damage will result just the same only we're talking lots more money !! So, my question is, does the machine really need it or does it just make you feel better to do it? Oh the Co. that does all the testing does not sell oil , oil filters or engines. Tim

You're right Tim. Add to that the many different riding styles and the variables are too many to make an over all statement about oil, oil changes, and filter replacement. Oil analysis after replacement to determine the condition and contaminants is the only way to know if your schedule is valid and if any problems are developing in the engine. I remember the phrase "if you can't measure it, it's only speculation" being drilled into my head long ago when starting an analysis of anything. One other data point would be what is done in the light aircraft maintenance shops, cut the top off the filter, spread the elements pleats, and give it a good looking over with a magnet and a bright light. But, because of the cost or the inconvenience the general rule of thumb has become 3000 mile oil and filter change. Seems to work for most people, even me.

1flyer said:

You're right Tim. Add to that the many different riding styles and the variables are too many to make an over all statement about oil, oil changes, and filter replacement. Oil analysis after replacement to determine the condition and contaminants is the only way to know if your schedule is valid and if any problems are developing in the engine. I remember the phrase "if you can't measure it, it's only speculation" being drilled into my head long ago when starting an analysis of anything. One other data point would be what is done in the light aircraft maintenance shops, cut the top off the filter, spread the elements pleats, and give it a good looking over with a magnet and a bright light. But, because of the cost or the inconvenience the general rule of thumb has become 3000 mile oil and filter change. Seems to work for most people, even me.

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Doens't work for me. Waste of $$. As you pointed out - unless you have an analysis done, it's all speculation.

So.. I did.

It's in PDF format - so if you're on dialup it might take a few minutes (one page)

http://www.eilenberger.net/K75S/C21138.pdf

This was with Mobil-1, 15W-50 (Red Cap) which was in the bike for about 10 months and 6,000 miles. From the readings and additive levels in the analysis, I wouldn't hesitate to take it out to at least 9,000 miles (which is what I'm gonna do with the Mobil-1 in the bike now) and have another analysis done.

Changing oil at 3,000 miles may make you feel good - but it really does nothing useful for the K bike engine.

Current good synthetics appear to be good for 15,000 miles or so on BMW car engines. I don't see a lot of reason a K bike engine would be much different.

Note - one mistake on the report. They listed it as 15w-40 oil, but if you look at the SUS-Viscosity, the number is more iin line with a 50 weight oil at 210F.

Also note the level of "insoluables" - this is DIRT. It's about 1/2 of what would normally be expected at 6,000 miles... an indication that the full-flow filter in a K bike (and I only use BMW filters) is doing it's job just fine.

The high flash point means the oil will resist burning, so there shouldn't be any varnish deposits forming in the engine.

Jeff's articles (pointed to above) - are really great, and he and I have had some long discussions about the results.

The results Jeff got were of new oil, unused. While he didn't draw any conclusions in the articles, I did. It seemed apparent to me that Mobil 1 and other synthetics are formulated for EXTENDED use.

If you look at the high-pressure additives - these are lower than the amount in some lesser oils since the synthetic is very unlikely to suffer from film-breakdown (metal to metal).

The acid neutralizing additives in the synthetics typically are significantly higher than lesser oils since the oil engineer expects the oil to be used longer and exposed to more acid (from combustion) that needs neutralizing.

The analysis I had done did reveal that Mobil is adding some molydenum to the oil (a high-pressure additive) along with other additive levels that may be a bit different from the oil Jeff tested (his were done in 1999). It also revealed that the zinc and phosphorus levels are well within specification for this oil - so high-pressure additives are holding up well.

What this all means is oil engineering continues to evolve. The Castrol GTX you used 10 years ago is nothing like the GTX on the shelf today.

Sorry - went a bit long. My point is - without an analysis you have NO idea what your actual change interval should be. The analysis I had done cost $35 - less than the cost of one oil change at a dealer. Money well spent IMHO.

Best,

oil

You know, the hostility is not appreciated, nor does it sit well with the intellignece statements (claims).

nor does it belong in this forum.

As R&D manger and Bonneville speedruns Crew Chief for Luftmeister, i did a lot of oil analysis, built a LOT of engines, and know more about the Kbike than 90% of the beemer bikers out there. But I do not go around bad-mouthing other people.

I was also a development engineer in high powered sattellite uplink transmitters for Hughes for 10 years. But i don't slam the dish network.

My information comes from a rather thick log book on oil analysis taken in the late 80's. The information used "control" bikes to establish a common point of reference in order to validate the data. One test on one bike is hardly scientific. Even if the data is impressive.

I use Mobile 1 myself and i change it every 3000 miles. If that makes me crazy, then I'm crazy. And proud of it. I've got over 50,000 dollars into that bike and it is an irreplaceable keepsake to me. Besides, it took 2nd place in "Modified K" at the rally, and i didn't even clean it.

It makes over 200 real-world rear-wheel Horse power (Branch flowmetircs dyno) and is doscile enough to safely drive through a buisy school zone. I also obey the speed limit.

So, I will expand on my statements a little here.
My circa late 80's data shows that VI additives dissipate in 3000 miles in my turbo bike, all 3 bonneville turbo/nitrous bikes, both control bikes, and in my pickup truck. I don't see any reason to believe that has changed as it would cause less oil to be sold. However, in the syntetic market, it could very well have changed as it is a very small market.

Is Mobile 1, or amsoil a better oil than it was in 1989? That's entirely possible. Is Castrol GTX any better? I doubt it. But, that does not make it a bad oil.

It is like 55w incandescent light bulbs. They are not designed to last 500 hours, they are designed to fail in 500 hours. It is marketing, driven by greed.

I wouldn't hesitate to use Castrol GTX in a stock water cooled bike. Not for a second. But if you truly love your bike, as i do, syntetics is the only answer.

Mark Volkomener
Crazy turbo-Kbeemer rider and damn proud of it.

I welcome your comments, but keep it cordial, please.

I was going to reply here at length to Mark, but decided not to, except a few points:

1. Data taken on oil in the past 2 months to me has more validity than oil data taken 15 years ago.

2. Oil use and breakdown in a turbo powered engine - especially if the turbo is oil cooled - is MUCH more severe than on a normal water cooled bike. It wouldn't surprise me to see viscosity breakdown on a turbo'd engine. That data doesn't really apply to normal K bike engines - which is what we were discussing here.

3. And this is for everyone - if you feel I insulted you with facts (or any other way) - please email me DIRECTLY. Do not post a message to that effect here. Those messages will be rather quickly removed. In this case - I don't see where I insulted anyone, but perhaps Mark thinks otherwise.

END OF DISCUSSION.

Oh - the quote in my sig - isn't mine. It was from Albert Einstein.