Join Date: Feb 2005
Location: LIncolnshire, , United Kingdom
Model: 1993 GL1500SE(P)
My GL1500 has about the same mileage on it as yours and I switched last year to 15/50w Semi Synthetic. The engine is a lot smoother with this oil and gear changes are the best they have ever been.
For those that missed this the first time (and I change oil and filter every 3,000 miles)
I have been in contact, for some time, with an "oil expert" who works in the motor racing business and he has given me some very good tips.
As my Wing now has 86k on the clock I asked him should I change from my exisiting oil , Semi Synthetic 10w-40 and asked him to explain what 10w-40 , etc meant.
This is his reply (edited).
[align=left] Basically you have two descriptors of an oils viscosity, the 'winter' and 'summer' number. the designation was left over from the time of monograde oils where in teh winter you got an oil for how well it flowed at cold temperatures - a 20W being more viscous than a 15W etc. For the summer weight, start-up wasn't so important and it was more about theviscosity of the oil when hot, and again, a 50 would be more viscous than a 40 etc.[/align] [align=left][/align] [align=left]A lot ofpeople mistakenly think that the numbers are related - they are not!! these are arbitrary numbers used to define a viscosity range that the oils falls in according to seperate hot and coldviscosity tests. Therefore a20W-20 is not the same viscosity whencold and hot.The winter (W) number defines the dynamic viscosity of the oil when cold, and the summernumber defines the kinemataic viscosity ofthe oil at 100deg C.What's important to remember is that every oil thins down with increasing temperature, and something like a 10W-30 will thin down a lot more than a 5W-50. [/align] [align=left][/align] [align=left]So basically it's as you say below. a 10W-40 and a 10W-30 have exactly the same cold temperature performance, but athigh temps, the 10W-30 is less viscous.[/align] [align=left][/align] [align=left]Something with a thicker high temp performance therefore would not be a bad idea for ultimate protection, especially in warmer weather. the only real downside to using these thick oils in terms of performance is that you get a little more viscous drag from the shearing of the thicker oil in bearings etc so this saps a little power, but still, BMW M series cars, and touring cars run a 10W-60 for protection so the power loss clearly is not huge. (other than purely oil characteristics, viscosity *can* point towards the quality of an oil in some cases but that isn't really relevant info - let me know if you need to know more about base oil quality tho).[/align] [align=left][/align] [align=left]It's something I do (or at least I like to, when I'm feeling a bit flush) - I use a 10W-50 in the summer and a 5W-40 in the winter. [/align] [align=left][/align] So with the conditions your bike see's (I don't really ride in the winter cold) you don't really need to worry about the W number.if you can find it,it would be good tho not essential going to a 10W-50 oil, the margin of protection that a 60 will give you over a 50 is arguably quite small (smaller than the jump from 40 to 50 anyway). the 10W-50 oils tend to be fully synthetics which should be a good thing, i don't know if there's any feedback from the owners club about the use of a full synthetic? but I'd recommend that you give it a go.
As a result I now use semi sythetic 15w-50 and my Wing really runs well on it. I definitely have noticed a difference.
Hope this helps ?
1993 GL1500SE 114,000 and Rising
North East Lincolnshire, UK