Oil viscosity, what is best.

[mxz600]

Another thread on oil. I'm starting a new thread because I didn't want this buried in the "Best oil" thread. This is just to try and clear up some confusion over which viscosity a person should use, not about which brand is best or the synthetic over blends argument. I have been reading differing opinions on what's best as far as 5W-40, 10W-40 and so on. The fact is it doesn't really matter as the important number is 40. At operating temperature they are all 40 weight oils.

Below is a link about oil viscosity.

http://www.synthetic-motor-oil-air-filters.com/amsoil/0w-30-5w-30-10w-30.htm

 

[scudrunner]

I will agree for the most part, but the bottom number is important depending on where you live. I live near Galveston, gets to a heat index of 115 in the summer with about 70+ % humidity. I still use 10 wt oil to ensure the oil moves quickly once the engine is started. If I lived way north, I would probably be using 5W40. But you are correct, once you get the juices flowing, the real number is 40.

 

[j45p3r]

I'll ride mine as cold as 25*F and I have no problem using 10w in the Spyder. If I were riding 15F or colder I'd probably switch back to using the 5w.

 

[BajaRon]

I agree that that bottom number is also important as a 10w-40 oil will function differently than a 5w-40 oil throughout the temperature range.

5w oil was originally used for very cold weather and then adopted as a fuel saving lubricant. 5w is very thin oil. That's what many use in their front forks as dampening fluid.

Additives are used to get the higher number. The bigger the spread between the high and the low number the more additives have to be used. Oil does not break down but additives do. Cheap additives can break down very quickly.

Amsoil shows test results on some oils that do not maintain their ratred viscosity very long at all. They go bad long before 3,000 miles. Add to this the additional heat and crushing force of having to lubricate the transmission and you can see where low quality additives are not a good idea.

I like 15w-40. It narrows the span of viscosity giving me more oil (which does not break down) and less addititives (which do break down). 15w is plenty thin enough to pump quickly at start-up. Unless you are starting your engine in VERY cold conditions it will flow just fine. Most people in really cold climates (who are crazy enough to ride in Zero weather) store their Spyder in somewhat less harsh temperatures. It's not the outside temp that gives you problems, it's the temp of the oil at start-up that matters.

Once the engine is at opperating temperature the oil doesn't care if it's Zero degrees outside.

If I were running in +90 temperatures all the time I would use 20w-50 oil. That is what I ran in my motorcycles when I lived in California. A little thicker oil might cost me a few 10ths of a mile per gallon but my engine (and especially transmission) would certainly love me for it.

 

[SpyderWolf]

I have also thought about running 20w-50 in my Spyder during the summer months. It is what I used to run in my GSX-R all the time, and my car currently uses it as well.

 

[BajaRon]

I have also thought about running 20w-50 in my Spyder during the summer months. It is what I used to run in my GSX-R all the time, and my car currently uses it as well.

I haven't run it in my Spyder but I may this summer just to see. It certainly won't hurt anything.

I know in my motorcycles I get smoother shifting and I was generally pleased with it in hot weather.