Ordering some bits to do a service on my "new" car. Not sure when the last one was done, but the oil looks fairly nasty. 1: Which oil? It's done 167000 miles. 10W40 or heavier? Haynes recommends 10W40 up to 15W50. Leaning towards shell HX5 15W40 - fairly cheap at Euro. 2: Will the oil drain OK with the car on ramps (front only) or does it need to be level. 3: 7 litres is a lot of oil... What if I buy a new gallon can and mix it with a couple of litres of whatever it is I have left in the shed? There's the best part of a gallon of fresh "texaco turbodiesel" oil in there, the label's missing on the can, and it could be ten years old... but seems a shame to waste it. 4: If I replace fuel filter (and pre filter) will I need to replace O-rings and if so where do I get them? Thank y'all.