25 W 60 is way too thick for the engine. The oil pump will pump it but the engine needs a thinner oil. Get it out fast and put back in the thinner oil. An oil that's too thick will starve the bearing surfaces of oil. K engines are built to good tolerances. Even in a hot climate you would never use one of those oils. The knock is most likely before the oil pressure builds up on the bearings and possibly the tensioner.

I agree that "lifetime" trans oil is BS. My brother's 525 car has that and I don't buy into that.  It's a known fact that oil breaks down over time and miles.

My understanding is that "high mileage" oil contains some additives the helps swell/seal old rubber seals.

I've never heard of a K bike failing for oil-related reasons. You could probably run them on peanut oil and not have a problem.  (That's a joke, not a suggestion.)

Most modern engines only use a 5 or 10w grade oil. A 25w is quite thick and takes longer to build up pressure from cold. Over time with stop start that increases wear. To use that grade in winter would definitely not be good, I still would not put that oil in. I can't remember which grade goes in but I think mine is on 10w40. The K does go back to 1983 but the engine was quite advanced at that time. The oil pu

Whatever about the oil I reckon it is the cause of the knock because I have come across that before.

@BritMotorWorx wrote:

bikerboy wrote:

@Kyle10 wrote:

Many people believe that higher-mileage engines benefit from thicker/heavier oils, which is not really true. Contrary to popular belief, thinner oils work far better in that they lubricate better on startup and continue to lube smaller passageways better throughout the heat cycle. 

That being said K75cster, would a thicker oil leave a heavier deposit on worn parts in an older motor for the next start up?   Also as the engine wears wouldn't a thicker oil leave a thicker film around the worn parts thus reducing vibrations caused by the greater tolerances?   I have added Morey's engine oil conditioner to my old Honda car and it noticeably quietened the engine noise and it is very slippery,sticky stuff!   My old Beemer has over 60,000 miles and always wondered about additives in old motors to thicken the oil slightly, at the same time leaving a thick oil deposit on all surfaces for start up?       

Yep I would think so, but I liked the morey's gearset sample model sitting on the counter of the spare parts store and would turn the handle everytime I went in there, would have to think it would do for our bikes what it did for the cars I put uit in. Bikerboy I would put diesel in the tank not to use as fuel but to keep the tank clean, but then again that might be a farce as well as using it to stop the pump drying out, anyone want to advise??

Here is the O'Fishal guide to oil

My take is that if your radiator is up to handling the heat transfer load in worst case scenario then better to minimise heat loss from other areas like engine surfaces. Operating temperature will be reached more quickly from cold start and rate of cooling when engine off will be slowed.
My Isuzu diesel had a thermal jacket covering most of the block, head and rocker cover - I think an indication that it was designed with longevity as a primary consideration. Had to be good for something as it only developed 55kW from its 2.5 litres (diesel!)

92KK K100LT 193214 wrote:25 W 60 is way too thick for the engine. The oil pump will pump it but the engine needs a thinner oil. Get it out fast and put back in the thinner oil. An oil that's too thick will starve the bearing surfaces of oil. K engines are built to good tolerances. Even in a hot climate you would never use one of those oils. The knock is most likely before the oil pressure builds up on the bearings and possibly the tensioner.

changed oil to 10w 40 and the  old girl is back to her old self. thanks for that