BajaRon
Well-known member
Why use 10W40 when the manual says to use 5W40? It cracks me up when people say they use it with "no issues." Maybe years down the road the 2nd or 3rd owner will experience the "issues."
There are actually a number of good reasons to use 10w-40 as opposed to a 5w-40.
1- The larger the gap between the low number and the high number, the less stable an oil is. If you are using a mineral oil with an additive package (which is what most 'Synthetic' labeled motor oils are), it takes more additive to get this wider spread. Additives are there to protect the weaker mineral oil molecules from shearing and other forces which break the oil molecules down and degrade their lubricating properties. Additives are not lubricants, and they do break down. Once these protective additives start to go away, the weak mineral oil molecules tend to lose integrity quickly. This is why the BRP oils tend to shear down to 20 weight at around 5,000 miles according to the oil analysis testing we've seen.
2- The low number of these 2 is only designed to give a relative viscosity at cold start-up. While cold start-up viscosity is important, it only needs to be thin enough to deliver adequate lubrication to vital parts during this very short period of time. If you are storing your Spyder in sub-zero temperatures, then a 5w oil would certainly be advantageous. However, it is probably a very rare Spyder which ever sees this kind of cold start-up temperature. This means that you are sacrificing at least some stability for a cold start-up viscosity that you will never need.
It is also interesting to note that true synthetic oils like Amsoil, Schaeffer, etc., being engineered at the molecular level during the refinement process have much stronger molecules. This is why they are able to achieve multiple viscosities and are inherently more stable and able to resist shearing and other destructive environments with minimal additives. We consistantly see Amsoil tests coming back in the low to mid 30's at 10k as opposed to BRP and other oils at 20w at the same mileage.
If you really want to know what is going on with your oil, have it tested. It's easy and not that expensive. And then you don't have to take someone else's word for it. But be prepared. The results may surprise you.
People truly do get personally invested in their brand and the oil debate will certainly rage on. I do not expect that my 2 cents will change anything. But it is always an interesting discussion.
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