gear box oil

not so much a question.but i recently asked what oil would be good to use in my gear box/transfer and diffs and most responses were to use fully synthetic good idea but have you seen the price.any way i changed all my oils on sat using valvoline synthetic blent $28 for 4ltrs in gear box/front diff/transfer case and caltex lsd oil in rear(non synthetic)$5 a litre.first thing i noticed straight away is so much easier to change into second gear in the morning used to nearly have to double clutch for a while untill oil got warm and seondly whine in 5th gear wich was quite noisy is hardly noticable so i car now turn stereo down a little.i havnt had it in the mud yet so not sure how diffs are.but so far im happy.ill see how they go at easter only 18 days to go woooo hoooo.looking foward to easter at jamieson