10w40 vs.15w50

[MN_Scrambled]

I just spoke to my mechanic about this. I specifically noted that the Triumph owner's manual recommends "synthetic 10w-40 or 15w-50." His reply was 10w-50 synthetic. He said it was the best of both worlds. Curious if anyone agrees/disagrees.

[IrlMike]

Originally Posted by MN_Scrambled

I just spoke to my mechanic about this. I specifically noted that the Triumph owner's manual recommends "synthetic 10w-40 or 15w-50." His reply was 10w-50 synthetic. He said it was the best of both worlds. Curious if anyone agrees/disagrees.

The SAE numbers don't quite give the full story. There's a range of viscosity for each number. Whilst the higher number is specified at 100 deg C, which is close to normal engine operating temperature, the lower number is specified at 40 deg C which is a lot higher than the usual range of cold starts a lot of the time. Added to that, the viscosity vs temperature is non-linear, so a small difference within, say the 10W range, at 40 deg, can mean a big difference at 20 deg.

It can be worth looking at the actual cSt viscosity numbers, if given by the maker, to decide which brand/type within an SAE number range best suits the ambient temp range you'll be riding in. For example, you may decide changing brand/type gives enough viscosity difference to stay within the nominal 10W 40 range throughout the year.

Here's a site which graphs out the viscosity to compare different oils from entering the maker's 40C / 100C data:

http://www.widman.biz/English/Calculators/Graph.html

It gets interesting (if one can say that in an oil thread haha) when trying to decide whether to change for summer/winter or run the same oil for the year. Generally the oils with higher levels of synthetic base stock (& more $$) give a better range of performance (in viscosity terms) vs temperature.

I've seen that info, mentioned above, about viscosity retention before (losing 30% over 1500 or so miles). However, for synthetics at least, oil analysis data posted at the bobistheoilguy forum (enter at your peril lol) would suggest it's very much less than that, probably not an issue at all with full synth over 6k miles. (But, as ever, it's hard to know if shorter change intervals offer other advantages, or not!)

Bottom line is, if a bike is being kept for the long haul, there's possibly choices to be made (in actual viscosity) taking account of usage conditions & annual miles. How much difference it makes is anyone's guess

[Stoltec Moto]

Originally Posted by IrlMike

The SAE numbers don't quite give the full story. There's a range of viscosity for each number. Whilst the higher number is specified at 100 deg C, which is close to normal engine operating temperature, the lower number is specified at 40 deg C which is a lot higher than the usual range of cold starts a lot of the time. Added to that, the viscosity vs temperature is non-linear, so a small difference within, say the 10W range, at 40 deg, can mean a big difference at 20 deg.

It can be worth looking at the actual cSt viscosity numbers, if given by the maker, to decide which brand/type within an SAE number range best suits the ambient temp range you'll be riding in. For example, you may decide changing brand/type gives enough viscosity difference to stay within the nominal 10W 40 range throughout the year.

Here's a site which graphs out the viscosity to compare different oils from entering the maker's 40C / 100C data:

http://www.widman.biz/English/Calculators/Graph.html

It gets interesting (if one can say that in an oil thread haha) when trying to decide whether to change for summer/winter or run the same oil for the year. Generally the oils with higher levels of synthetic base stock (& more $$) give a better range of performance (in viscosity terms) vs temperature.

I've seen that info, mentioned above, about viscosity retention before (losing 30% over 1500 or so miles). However, for synthetics at least, oil analysis data posted at the bobistheoilguy forum (enter at your peril lol) would suggest it's very much less than that, probably not an issue at all with full synth over 6k miles. (But, as ever, it's hard to know if shorter change intervals offer other advantages, or not!)

Bottom line is, if a bike is being kept for the long haul, there's possibly choices to be made (in actual viscosity) taking account of usage conditions & annual miles. How much difference it makes is anyone's guess

Tribologist? If not, consider a career change.

[Joe Houle]

I run 15w-50 Mobil1 in my race car. It is a vintage Formula Vee with a 1968 1200 VW engine.

It is built VERY loose. I need that weight or it just won't hold oil pressure at idle on the grid.

its thick.

thats all I have to add

[MN_Scrambled]

Originally Posted by IrlMike

The SAE numbers don't quite give the full story. There's a range of viscosity for each number. Whilst the higher number is specified at 100 deg C, which is close to normal engine operating temperature, the lower number is specified at 40 deg C which is a lot higher than the usual range of cold starts a lot of the time. Added to that, the viscosity vs temperature is non-linear, so a small difference within, say the 10W range, at 40 deg, can mean a big difference at 20 deg.

It can be worth looking at the actual cSt viscosity numbers, if given by the maker, to decide which brand/type within an SAE number range best suits the ambient temp range you'll be riding in. For example, you may decide changing brand/type gives enough viscosity difference to stay within the nominal 10W 40 range throughout the year.

Here's a site which graphs out the viscosity to compare different oils from entering the maker's 40C / 100C data:

http://www.widman.biz/English/Calculators/Graph.html

It gets interesting (if one can say that in an oil thread haha) when trying to decide whether to change for summer/winter or run the same oil for the year. Generally the oils with higher levels of synthetic base stock (& more $$) give a better range of performance (in viscosity terms) vs temperature.

I've seen that info, mentioned above, about viscosity retention before (losing 30% over 1500 or so miles). However, for synthetics at least, oil analysis data posted at the bobistheoilguy forum (enter at your peril lol) would suggest it's very much less than that, probably not an issue at all with full synth over 6k miles. (But, as ever, it's hard to know if shorter change intervals offer other advantages, or not!)

Bottom line is, if a bike is being kept for the long haul, there's possibly choices to be made (in actual viscosity) taking account of usage conditions & annual miles. How much difference it makes is anyone's guess

Wow, just when you think you've gone and started to understand something, it gets more complex!

Thanks, appreciate the info!

[bri]

DOSE ANY BODY RATE THIS ? WOULD IT DAMAGE MY 2001 SPEEDY ?

http://www.ebay.co.uk/itm/MOTUL-MOTO...#ht_1435wt_999

[pritch]

[QUOTE=bri;2142900]DOSE ANY BODY RATE THIS ? WOULD IT DAMAGE MY 2001 SPEEDY ?

I sincerely hope not. That's what I'm running in my 2009 - but in 10/40.
Either is OK according to the manual.

The workshop I used for the service sells Motul. I'd be happy with that or the Mobil 1 bike oil.

[lgregory]

You will notice no differwence if you go with Mobile One 20/50 V Twin available at Auto Zone. Especially a good choice in warm climes.

Originally Posted by 1peter

It won't cause any issues Peter1 but i do agree that 15/50 is quieter and changes gear with less of a clunk than 10/40. I've got Motul 10/40 in my bike now and will go back to Mobil 15/50 when i do the next change. I only went to Motul 10/40 because i got my 20,000km service done and the dealer only uses Motul oil + my bike uses a little oil and i wanted to try something else to see if there is any difference in consumption.

[SavageSS]

Sorry to dig up an old thread. I'm interested in the 10w40 vs.15w50.
I've got a 2012 S3, manual recommends either 10w40 or 10w50.

Could I jeopardise warranty if going for a 15w50?

Also temps rarely get below 0°C (if at all) , summers can and do get over 40°C what would be best oil 15w50 although not stated in the Owner's Handbook

[Speed3]

Originally Posted by SavageSS

Sorry to dig up an old thread. I'm interested in the 10w40 vs.15w50.
I've got a 2012 S3, manual recommends either 10w40 or 10w50.

Could I jeopardise warranty if going for a 15w50?

Also temps rarely get below 0°C (if at all) , summers can and do get over 40°C what would be best oil 15w50 although not stated in the Owner's Handbook

Ive run 15/50 for most of 43,000 miles. It's getting harder to find, so I have been using Mobil 1 10/40 M/C. You can't go wrong with either at the temps you described.