be careful with the waste oil,you have to filter it and de water it,to de water there are a few ways you can do this,you could filter the oil,then let it settle fora few weeks and then drian off the water,as water will go to the botton of the tank,one person in know filters the oil then heats it for a week to pull the water out,but there is a smell doing this,ok if you have a remote garage/lockup...
if you dont filter and dewater you will have running problems,if you have a bosch pup fitted will be able to run on straight oil,some other make of pumps have rubber seal in them and they rot over a period of time as veg oil can be acidic to rubber,but bosch pumps dont seem to suffer from this,this are loads of site on the web to point you in the right direction,try vegieburners.
been runnng my 1998 cherokee on and oil mix for near 4 years,runs sweet as a nut,cold weather can lead to hard cold starts,leaving a heater under the ungine bay for 30mins in real cold weathrr works wonders,i leave mine under the car overnight and it comes on via a timer,cold frosty mornings it starts no problem with that little bit of heat under he hood/bonnet,once started and warmed up it will run fine for the rest of the day,hot summer weather you can use straight new veg oil if you can get it cheap enough from costco or local wearhouse in 5 gal drums.
best of luck