RCMAd:
This is fine. Most fuels start at 10% and go up/down maybe one percent or two depending on nitro content.
e.g. Byron Race fuel II gen 20% nitro contains 11% Oil
Byron Race fuel II gen 25% nitro contains 10% Oil
Maxxy's 30% nitro contains 8% oil and lastly Tornado fule 16% nitro contains 12% oil.
The problem then becomes the quality of the oil.