You don't state what pest you are treating for in your lawn however, when using Permethring SFR 36.8% in your lawn the most common rate used would be .8 oz per gallon of water per 1000 sq. ft. When it states using 4-25 gallons of spray volume, it is telling you to be sure that you are getting a complete coverage for the area that you are treating. So if it takes you 1 gallon of water to treat the 1000 sq. ft evenly then you would use the .8 in 1 gallon. Should it take you 2.5 gallons you would use the .8oz in 2.5 gallons of water to cover that 1000 sq. ft evenly.
There is not a set temperature required for using Permethrin SFR, it is not an issue when mixing most products and most of the time we suggest something along the lines of warm or room temperature water.
Permethrin SFR will only control insects. Please take a look at our selection of Animal Repellents for products that can be used to keep rodents, squirrels, and rabbits away.
These products should not be mixed together. There is no valid reason to mix Onslaught and Permethrin SFR together. They are both synthetic pyrethroids so there would be nothing to gain by mixing these products together. Making a pesticide too strong can actually backfire. Areas that are treated with this overly concentrated spray will be repellent and insects will simply avoid the treated areas prolonging the infestation.