15w50 in a 1200/1250 LC - Long term tests anyone ? (Not an oil thread 🫣)

MotoRevive

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I'm looking for case studies of people who have run a heavier 50 weight oil in their liquid cooled BMW. Specifically the 1200. Which are meant to run 5w40

And if they have found any problems or benefits over 10,000 miles of use.

Thicker oil arguably provides more long term protection. But also more friction. So lower mpg. Harder cold starts and more strain on small batteries.

Manufacturer oil recommendations are based as much on economy and efficiency (Euro standards) as much as they are with engine health. We can see this in the car industry as oil weights get lower and lower.. Even zero weight oils to improve efficiency. At the cost of catastrophic engine failures.

This can also be seen with the retrospective swap to 80 oil for BMW bevel drives from 75w90.

However, swapping engine oil isn't that simple. Engines could have tolerances that a thicker oil doesn't penetrate. Or
oil jets that can not spray far enough etc.

Any case studies here ?

Cheers.
 
often wondered about this too,, my bike does the majority of miles on trips to places like spain, southern france italy etc, and i dont run it through winter so have thought of trying a 10w 50 in it, like my ktm 1290 uses,
watching with interest :)
 
I doubt whether one increment increase in viscosity is going to do any harm.
I read that some of the cars running very thin 0W20 have heavier options for arduous conditions.
 
According to Ai and gathered information, (taken as a reply, not a given fact)

Running 15W-50 instead of the recommended 5W-40 can reduce cold-start protection and may slightly increase engine wear in cooler conditions, since 15W-50 is thicker when cold.


Impact of Using 15W-50 Instead of 5W-40 Oil​

Cold-Start Protection​

Using 15W-50 oil instead of the recommended 5W-40 can lead to reduced cold-start protection. The thicker viscosity of 15W-50 when cold means it does not flow as easily as 5W-40, which can result in:

  • Increased Engine Wear: The engine may experience more friction during cold starts, potentially leading to premature wear over time.
  • Difficult Starts: The thicker oil can make starting the engine more challenging in cooler temperatures.

Long-Term Effects​

While using 15W-50 oil may not cause immediate damage, the long-term effects can include:

  • Increased Wear: Continuous use of a thicker oil in conditions where a thinner oil is recommended can lead to higher wear rates on engine components.
  • Reduced Efficiency: The engine may operate less efficiently, affecting fuel economy and overall performance.

Recommendations​

To avoid potential long-term damage, it is advisable to:

  • Follow Manufacturer Guidelines: Always use the oil viscosity recommended in the motorcycle's user manual.
  • Consider Operating Conditions: If riding in colder climates, stick with the recommended 5W-40 for optimal protection and performance.
In summary, while using 15W-50 oil may not cause immediate issues, it can lead to increased wear and reduced efficiency over time, especially in cooler conditions.

Explore More​

What are the long-term effects of using 15W-50 oil in a bike engine?
Using 15W-50 oil in a bike engine can provide better temperature stability and protection under heavy loads, making it suitable for high-performance or older engines. However, if the engine is designed for a different viscosity, it may lead to increased wear or overheating over time.

Imho, I have always only ever ran the recommended oil stated in the Bike manual, sticking to what manufacturers say is best as they did spend Β£millions on development studies, while the aged biker only wants what's best for his/her engine, with perhaps less cost to them, choice is with the owner. Hope this helps.
 
Last edited:
I'd like to see the evidence for increased wear.
We already know that the manufacturers aim for reduced friction and therefore reduced emissions and fuel consumption & road tax above everything else and that includes longer term reliability. In the car market especially, fuel consumption and emissions drive sales above everything else.
 
HxH said:
According to Ai and gathered information, (taken as a reply, not a given fact)

Running 15W-50 instead of the recommended 5W-40 can reduce cold-start protection and may slightly increase engine wear in cooler conditions, since 15W-50 is thicker when cold.


Impact of Using 15W-50 Instead of 5W-40 Oil​

Cold-Start Protection​

Using 15W-50 oil instead of the recommended 5W-40 can lead to reduced cold-start protection. The thicker viscosity of 15W-50 when cold means it does not flow as easily as 5W-40, which can result in:

  • Increased Engine Wear: The engine may experience more friction during cold starts, potentially leading to premature wear over time.
  • Difficult Starts: The thicker oil can make starting the engine more challenging in cooler temperatures.

Long-Term Effects​

While using 15W-50 oil may not cause immediate damage, the long-term effects can include:

  • Increased Wear: Continuous use of a thicker oil in conditions where a thinner oil is recommended can lead to higher wear rates on engine components.
  • Reduced Efficiency: The engine may operate less efficiently, affecting fuel economy and overall performance.

Recommendations​

To avoid potential long-term damage, it is advisable to:

  • Follow Manufacturer Guidelines: Always use the oil viscosity recommended in the motorcycle's user manual.
  • Consider Operating Conditions: If riding in colder climates, stick with the recommended 5W-40 for optimal protection and performance.
In summary, while using 15W-50 oil may not cause immediate issues, it can lead to increased wear and reduced efficiency over time, especially in cooler conditions.

Explore More​

What are the long-term effects of using 15W-50 oil in a bike engine?
Using 15W-50 oil in a bike engine can provide better temperature stability and protection under heavy loads, making it suitable for high-performance or older engines. However, if the engine is designed for a different viscosity, it may lead to increased wear or overheating over time.

Imho, I have always only ever ran the recommended oil stated in the Bike manual, sticking to what manufacturers say is best as they did spend Β£millions on development studies, while the aged biker only wants what's best for his/her engine, with perhaps less cost to them, choice is with the owner. Hope this helps.
Click to expand...
In mechanics and engineering, you quickly learn to ignore AI.

AI just scans forums, Reddit and any other unqualified or fact checked content off the Internet.

5884.jpg
 
Buckingham said:
I'd like to see the evidence for increased wear.
We already know that the manufacturers aim for reduced friction and therefore reduced emissions and fuel consumption & road tax above everything else and that includes longer term reliability. In the car market especially, fuel consumption and emissions drive sales above everything else.
Click to expand...
It is an absolute fact that the same cars (or engines) will have different oil specs depending on the market they are sold in.

With the less economically concerned markets generally specifying heavier oil for better protection and wear.

Thinner oil is a cheap and easy way to increase mpg and economy. And in the 'planned obsolescence' world we live in, this makes even more sense.

I have a 2015 1200GS with 45k. Once I get in back from Spain in the spring, I'm going to run it with 15/50 for a while to experiment.

Its got a clunky gearbox and a rattle from the clutch anyway. So I was going to strip the motor and do some research for future jobs.
 
Why 15/50 though?
If it`s a 5W-40 sourcing problem there are dozens of 10W-40 options available (i`m on 10W-40 at the moment on my 1250).
 
MotoRevive said:
I'm looking for case studies of people who have run a heavier 50 weight oil in their liquid cooled BMW. Specifically the 1200. Which are meant to run 5w40

And if they have found any problems or benefits over 10,000 miles of use.

Thicker oil arguably provides more long term protection. But also more friction. So lower mpg. Harder cold starts and more strain on small batteries.

Manufacturer oil recommendations are based as much on economy and efficiency (Euro standards) as much as they are with engine health. We can see this in the car industry as oil weights get lower and lower.. Even zero weight oils to improve efficiency. At the cost of catastrophic engine failures.

This can also be seen with the retrospective swap to 80 oil for BMW bevel drives from 75w90.

However, swapping engine oil isn't that simple. Engines could have tolerances that a thicker oil doesn't penetrate. Or
oil jets that can not spray far enough etc.

Any case studies here ?

Cheers.
Click to expand...
I am aware that the guys from Rapid Training were working with an oil company around 5 years ago. I don't recall which company it was, if I was told.

There were provided with a number of 1200/1250 GS's for long term testing.

It may have been additive testing, rather than oil itself.

May be worth asking.
 
Hann said:
Why 15/50 though?
If it`s a 5W-40 sourcing problem there are dozens of 10W-40 options available (i`m on 10W-40 at the moment on my 1250).
Click to expand...
It's got nothing to do with supply. It's the extra protection that a heavier '50' weight may provide

It's only really the second number that's relevant to me. The operating temperature viscosity. Not the winter weight. So to speak.
 
MotoRevive said:
In mechanics and engineering, you quickly learn to ignore AI.

AI just scans forums, Reddit and any other unqualified or fact checked content off the Internet.

View attachment 546970
Click to expand...
Imho asking Ai the correct Question in detail, will get a more precise answer.
i.e.
Question to Ai:- Will I die or get seriously ill after eating this type of Mushroom?
Answer:- Yes! Most certainly! Most humans, including animals that consume this type of mushroom perish, some may shit all day for weeks possibly months, fading away slowly. :green gri

Imho much like any bike fed on wrong engine oils! Death eventually happens.
Any advice is good advice, except when it's not, taken or left at owners choice!
 
Last edited:
HxH said:
Imho much like any bike fed on wrong engine oils! Death eventually happens.
Click to expand...

But this is the question

Is an oil incorrect just because it isn't what the manufacturer is possibly forced to recommend !

Over what is actually better for your engine.

There hasn't been a boxer engine ran on SAE 40 until Euro laws started getting much stricter.

I build and repair a lot of engines. It's my professional business. It's an interesting topic for me.

I do have a customer who has run 15w50 in his K1600 for the last 36,000 miles. The last valve check I did for him, his cams were like new. And his bike runs extremely quietly and smooth. Perhaps better than others.

But that doesn't mean that theory will automatically translate over to a 1200LC

Hence why I asked the question. πŸ‘πŸ˜Š
 
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Reactions: HxH
A I is a wonderful tool but never to 100% be relied on. I recently used it to source some front pads for my Ducati, ordered said pads from Sportsbike shop and as always took delivery the next day, opened both packets and set about taking my old pads out, turned out AI or rather SI as Mr Trump tells us we must now call it was wrong, completely wrong! quick call to SBS and the bloke said never ever rely on AI. they'd seen mistakes made like this on numerous occasions, I explained I'd opened both packs but they just said no problem return them then they'd send the correct ones out which they did!

Interestingly Ducati spec a 15w50 oil for my 1200 all singing all dancing 160bhp bike, same oil in fact as my twin cam BMW!
 
Pale Rider said:
A I is a wonderful tool but never to 100% be relied on. I recently used it to source some front pads for my Ducati, ordered said pads from Sportsbike shop and as always took delivery the next day, opened both packets and set about taking my old pads out, turned out AI or rather SI as Mr Trump tells us we must now call it was wrong, completely wrong! quick call to SBS and the bloke said never ever rely on AI. they'd seen mistakes made like this on numerous occasions, I explained I'd opened both packs but they just said no problem return them then they'd send the correct ones out which they did!

Interestingly Ducati spec a 15w50 oil for my 1200 all singing all dancing 160bhp bike, same oil in fact as my twin cam BMW!
Click to expand...
My KTM off-road bike and most Guzzies use 20w60.

KTM obviously want maximum protection for their chocolate cams.
 

A link to Amsoil, which has a guide to oils for all the different bikes.
 
Colm Cummins said:

A link to Amsoil, which has a guide to oils for all the different bikes.
Click to expand...
See post 11
 
It would be interesting to know if the thicker oil alters the oil pressure by any significant amount.
I mention this because i rebuilt a 2.0 l Land Rover Ingenium last year in a car bought as a non runner. Among other things i fit new pistons with rings into re-honed bores. I thought it would be a good idea to do a few hundred miles with 10w 40 semi synthetic oil to try and bed the rings in. I had nearly 100psi oil pressure at tickover and it leaked oil from all sorts of places. The oil pump has electronically adjusted volume control which was obviously set up for 0w30 fully synthetic oil. I swapped for the proper oil spec, and everything was good.

Stu
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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