yes it is true you can use used cooking oil in your diesels only if you are using the injection pump types not the crdi daw, have been using it since i have a friend who supplies me 60 liters a week and so far have consumed average of 40 liters a week although it saves you money it just lacks a little power i mean you really can note the less in pull but the car still climbs and pulls just that you will notice a drop in pull. Have used it pure, mixed whatever ratios. Started with 1.5 liters to 4 liters thats when diesel was only at less than 30 thats why it 1.5 liter per bottle per fill up of 100 peso diesel, but recently madmax168 tried hundred percent and it was okay daw so increased ratio sometimes i do run 100 when fuel is low so pour it in until i get to a station, hehehe for those interested tried it on a besta 2.7 , 2c fx, kia pregio, pajero 93 , and a 98 space gear, well so far they are all ok and yup using a high ratio of oil does clean out the carbon cause there is no more sulfur to burn and which creates the foul smell and the big amount of carbon. So it is safe, some would ask how safe okay the fx is still in the 150kms and still original state of injector the besta accumulated severl thousand of kms well used it with oil of 30 % to laoag had injectors repaired since it developed a leak as in it drips diesel so had to have gasket replaced and calibrated cost of 3000pesos the pregio and pajero space gear still in ok condition. But in case any of you guys do intend to filtering the oil is the hardest buy a .1 micron water filter and force it thru however i just juse a 1 micron well the filter in the vans are just 5 microns according to manufacturers specs so i guess its safe but even in 1 microns there will be this brownish liquid like or fine almost ash like particles still so just pour the oil carefully not to include the brown liquid like ash . But then if diesel gets back to below 30 then its not worth it, by the way have talked to mc do have a hard time getting thier oil have not tried jollibee thou