my friend has a rex and he switched from mineral oil to syn oil recently. He said he paid around $90 or somthing to actually switch.. i thought it was a bit pricey for an oil change but he said that was for something that needed to be changed in the car in order to use syn oil. Now that its changed, he says it'll cost him regular price.. $90 for an oil change sounds kinda........ expensive? i dont know if he got jipped or not.. and is it true you have to get something changed in the car before u switch to syn oil?