Starting to get into this whole service-your-own-Volvo thing. Have bought an oil filter from German&Swedish and now need some recommendations as to what grade of oil would be best. I am running a 1992 940T estate that currently has 145k miles on the clock. I know nothing about grades and whether an oil is synthetic or not, so all advice gratefully received. Any tips about the job itself would also be welcome, though I'm assuming that unscrewing the current filter and draining out the old oil from wherever the plug is under the engine will be straight forward enough. Thanks - Tim