I need to carry out a travel adjust on my Rebas so will be dropping the lowers.
I think the fork oil I have is a synthetic 7.5wt.
RS state I should be using 15wt.
Will a lighter oil cause issues?
no - just have to change it more frequently
It'll be fine. I've done it with no problems. It's not so much WHAT oil you use more than the fact that you actually do CHANGE IT! 🙂
I tend to use a slightly heavier oil in lowers as it is more clingy and less likely to end up pooled at the bottom. Have you seen the stuff in Maguras? It is like goose fat...
For the nth time on STW, the weight rating of an oil doesn't mean much. Even if you stick with one brand but differing oil types.
You need to know the viscosity in centistokes (cSt) at 40 degrees C, which all manufacture should (and most do) provide.
There is a useful list [url= http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid ]here.[/url]
From that list you will see (for instance), that 10wt Castrol Fork Oil is actually thinner than 2.5wt PJ1 Fork Tuner Oil!