Just a quick check to see if this is the right stuff to put in my K100LT ABS, its 5 litres worth which is more than 4 quarts, its also 10W40 which I think is right.

https://www.eurocarparts.com/ecp/p/car-accessories/engine-oils-and-car-fluids/engineoils/10w40-engine-oil/?521776011&0&cc5_245

Some K's don't like semi-synth as it leaks passed the seals. I haven't had this problem, but others have. If you want to be absolutely safe:

https://www.halfords.com/motoring/engine-oils-fluids/engine-oil/halfords-classic-oil-20w50-5l

I tend to use this in preference to the semi-synth.

Dai wrote:Some K's don't like semi-synth as it leaks passed the seals. I haven't had this problem, but others have. If you want to be absolutely safe:

https://www.halfords.com/motoring/engine-oils-fluids/engine-oil/halfords-classic-oil-20w50-5l

I tend to use this in preference to the semi-synth.

and its fine that its not 10W40?

Yes. It never gets cold enough in the UK to warrant the use of a 10-base oil. Now Germany... that's a different matter.

I have run the Triple QX and GSF's own Vetech brands of 10w40 and find them a bit on the thin side, I remember I once nipped into town on a hot day and half the sump disappeared..! Millers semi synth 10w40 was similar, but cheap Carlube 10w40 never got touched.

You can often get a really good deal from ECP or GSF, I got 20L of Vetech for £32.. So I stick with it, just keep an eye on the level. I'm currently using it in everything, wet clutches don't seem to be affected by it either - winner.

I'm also using Triple QX fully synth gear oil, 75w-90, and to be honest it seems utter pants - after ~7000 miles or so it was decidedly thin. I'll look elsewhere next time.

DBRMN wrote:

Dai wrote:Some K's don't like semi-synth as it leaks passed the seals. I haven't had this problem, but others have. If you want to be absolutely safe:

https://www.halfords.com/motoring/engine-oils-fluids/engine-oil/halfords-classic-oil-20w50-5l

I tend to use this in preference to the semi-synth.

and its fine that its not 10W40?

I used 10W40 Down Undah for a while. No worries.

Two Wheels Better wrote:

DBRMN wrote:

Dai wrote:Some K's don't like semi-synth as it leaks passed the seals. I haven't had this problem, but others have. If you want to be absolutely safe:

https://www.halfords.com/motoring/engine-oils-fluids/engine-oil/halfords-classic-oil-20w50-5l

I tend to use this in preference to the semi-synth.

and its fine that its not 10W40?

I used 10W40 Down Undah for a while. No worries.

Wow never realised it was so minimal the difference between them, this chart is very useful.

Snod Blatter wrote:I have run the Triple QX and GSF's own Vetech brands of 10w40 and find them a bit on the thin side, I remember I once nipped into town on a hot day and half the sump disappeared..! Millers semi synth 10w40 was similar, but cheap Carlube 10w40 never got touched.

You can often get a really good deal from ECP or GSF, I got 20L of Vetech for £32.. So I stick with it, just keep an eye on the level. I'm currently using it in everything, wet clutches don't seem to be affected by it either - winner.

I'm also using Triple QX fully synth gear oil, 75w-90, and to be honest it seems utter pants - after ~7000 miles or so it was decidedly thin. I'll look elsewhere next time.

So synth stuff is definitely a no go area. I think I'm just going to get some classic Engine Oil from Halfords, looks like a good idea.

"Myth #3: Synthetic engine oils can wear down seals in an engine and cause leaks. This is an often-cited myth. In fact, if your seals and gaskets are in good condition,synthetic oil will not leak in your engine. Synthetic oil has not been shown to deteriorate engine seals or gaskets."


Cenex Petroleum


Old seals or worn seals can lead to leaks, when using synthetic oils, but the oil doesn't cause them.

Two Wheels Better wrote:"Myth #3: Synthetic engine oils can wear down seals in an engine and cause leaks. This is an often-cited myth. In fact, if your seals and gaskets are in good condition,synthetic oil will not leak in your engine. Synthetic oil has not been shown to deteriorate engine seals or gaskets."


Cenex Petroleum

Oh but if you have terrible seals it has more chance of seeping through?

DBRMN wrote:Oh but if you have terrible seals it has more chance of seeping through?

See my edited post just above.

My experience with this issue of oil leaks after using synth oils goes back to the '70s when synthetics were becoming popular, especially during the first and second energy crises. 

I was a curious lad, prone to reading Popular Mechanics, Popular Science, Road & Track, Autoweek, of many other magazines in the school library and at home. In those pages the subject was much discussed. My motorbikes got regular oil changes using traditional oil, but they were newer, of mid to late '70s vintage. When I finally tried synthetic oil I had no such issues, until I put synth gear oil and synth engine oil into my 1970 R60/5 with about 40,000 miles on the clock. This time, after a while, I got seepage on the shift lever seal, and in the front crank seal. So I went in search of the reason. It turns out manufacturers, in the late '70s, had begun to use a larger quantity of Buna N elastomers mixed in to the seal stock (which had been around since the '30s, invented by IG Farber & company) which allows for a greater heat range in rubber, greater resistance to petroleums, and a longer life due to flexibility, etc. A 1970 BMW motorbike still had the brittle, older seals throughout. Over time I ended up replacing those seals with newer materials and lo and behold, only a worn shaft, that even a good seal wouldn't work well on, had any seepage. 

So, in the 'early daze', and beyond, yes, there were some instances of leakage, but it was the rubber composition that was the issue. Synthetic oils simply highlighted where a product needed to be improved. I highly doubt there are any NOS (new old stock) seals of the old type that are viable forty years later even if kept in proper storage. 

Imagine if one major industry, inherently reliant on another industry, was producing a product its partner could not use successfully? 

Myths linger.

Two Wheels Better wrote:

DBRMN wrote:Oh but if you have terrible seals it has more chance of seeping through?

See my edited post just above.

My experience with this issue of oil leaks after using synth oils goes back to the '70s when synthetics were becoming popular, especially during the first and second energy crises. 

I was a curious lad, prone to reading Popular Mechanics, Popular Science, Road & Track, Autoweek, of many other magazines in the school library and at home. In those pages the subject was much discussed. My motorbikes got regular oil changes using traditional oil, but they were newer, of mid to late '70s vintage. When I finally tried synthetic oil I had no such issues, until I put synth gear oil and synth engine oil into my 1970 R60/5 with about 40,000 miles on the clock. This time, after a while, I got seepage on the shift lever seal, and in the front crank seal. So I went in search of the reason. It turns out manufacturers, in the late '70s, had begun to use a larger quantity of Buna N elastomers mixed in to the seal stock (which had been around since the '30s, invented by IG Farber & company) which allows for a greater heat range in rubber, greater resistance to petroleums, and a longer life due to flexibility, etc. A 1970 BMW motorbike still had the brittle, older seals throughout. Over time I ended up replacing those seals with newer materials and lo and behold, only a worn shaft, that even a good seal wouldn't work well on, had any seepage. 

So, in the 'early daze', and beyond, yes, there were some instances of leakage, but it was the rubber composition that was the issue. Synthetic oils simply highlighted where a product needed to be improved. I highly doubt there are any NOS (new old stock) seals of the old type that are viable forty years later even if kept in proper storage. 

Imagine if one major industry, inherently reliant on another industry, was producing a product its partner could not use successfully? 

Myths linger.

very helpful thank you