Not to sure what type of chart your looking for. Your best bet is to check the fluid specification sheet for the fluid and see what it capable of doing and what applications it should be used for.
A good high quality universal tractor fluid should handle most applications that call for light weight/hydraulic fluids. Use a good high quality
UTF, or a
slightly thicker UTF with tackifier additive and for special applications calling for a
303 fluid.
As for gear oil, do not use a thiner viscosity fluid in it's place. If it calls for a heavy weight 80 to 90 weight gear oil use just that.
Whatever you decide to use stick with it. It is never a good idea to mix different manufacturer's lubricants. Different additive packages in the oils can end up canceling out any benifit's that they may provide and can sometimes cause seperation of the additives. If you pick a different fluid to go with, drain the whole system and refill with one type fluid and then use that same fluid to top off the system when needed.
As for shear strength and flash point you should be concerned. The specifications of the fluids you choose are very important. Cheap fluids are just that, cheap and have very small additive packages, low quality base oils and lower specifications. High quality oils are made with ultra refined base stocks, superior additive packages which make for high specifications and extended drain intervals and decreased wear. A good lubricant manufacturer should also provide used oil analysis (UOA) for free for their products.
UOA itself can end up saving you alot of money in the long run by detecting problems before they become critical. They are great for finding leaking head gaskets, fuel dilution, water contamination, wear metals (indicating something is about to break) and other fluid contamination that could cause a problem in the short term future.
Best advice is to buy the best quality lubricants you can afford. The better ones cost more at the start but are worth the investment. Increased drain intervals alone can recover the initial cost difference. Reduced break down frequency is also a added bonus along with better cold temp operation characteristics.
