I was going to run with Diesel engine oil for a few K mainly to give the starter Sprag a preventative clean. I am also planning to strip the oil/water pump as my oil pressure light started flickering at tickover a while back. At the start taking it a bit over tickover c.1000 rpm put the light out, but now I need to go to 1200rpm, suggesting its getting worse.

It occured to me that the pump might just be sludgy. Any thoughts on whether the diesel oil treatment might help in this respect too.

Maybe run a Thousand miles before deciding whether I need to strip the pump?
Cheers, Stu.

Stu: I'd get under the pump and check the wire first. I had something similar right back at the start of my K ownership and found that connector was more copper carbonate than copper.

Cheers Dai. I’m doing my pre-Dragon fettle. See you there.

You were quick! It was only decided last Thursday. Note the requirement for a Covid passport.

Hi Stu, I think running MINERAL Diesel engine oil is a good and safe way of removing the sludge that other oils cant reach. This is a good Preventative Maintenance practice. If the bike is to be stood over winter or long term storage,then change back to your normal oil. Hope this helps.

Stu,
I've added 50k to one of my bricks (87 100rt) and all I ever use is 15-40 in all my bricks. Hell some times I'll go 6-7k before changing. I'm sure some would say I'm crazy and I can't argue with that.

I have a few Ks and if I use 10W40 oils the oil light flickers when the engine is hot.

I have had issue on an oil pressure sensor before and to be honest the easier task is to check the wire and possibly swap the sensor.

I have reverted to 20W50 mineral and frequent changes and it has eliminated sprag clutch issues.

As for the diesel oils, anthing rated above the K spec is good, many oils are now suitable for both petrol and diesel engines.

I have foiund the K1100 particularly liklely to have a flickering oil pressure light in hot weather on W40 oils and never put less than a 50 in it now. Even the manual for K1100 has W50, so its a manufacturing thing rather than a defect.

I think you would need to be living in extreme weather conditions to warrant using an oil outside of what BMW recommend and that's stated in the rider's manual but 10w40 in a cold climate could be ok but I wouldn't. Definitely not a good grade to use in any warmer climates. I tried 10w40 in my old K100 a few years back and it rattled like a bucket of bolts. I suspect 40 is a little too thin and the pump is having a little trouble keeping the pressure up.... that can't be a good thing.
These days 15w50 works well for me.

Dai wrote:You were quick! It was only decided last Thursday. Note the requirement for a Covid passport.

Can’t spare a second at my age

Dai, Olaf. You nailed it. the lower of the two terminals was pretty mucky and a wiggly fit. Cleaned and pinched the light now flickers at 800rpm and stays out at 900. 
New filter and dino diesel change. That should give it all a good clean. Pig of a job getting the filter cover bolted back up, I couldn’t get the bolt holes to line up. I’ve changed the filter 4 or 5 times before and never noticed that the cover only fits one way. Blind luck every other time! I’ll take it 

Goooo-ud!

Spline lube tomorrow then all ready for the Dragon.