Ahh, that old chestnut. Well you could go to a main dealer and buy genuine. You can't go wrong. You could use a contact on here to get you genuine with some discount. Or you can go aftermarket.
I have changed more belts than I can remember and I have never had a problem and I have never used genuine. People always say 'Why take the chance?' Well, what chance? Why is there the assumption that aftermarket belts are inferior? If you start the engine and watch the belt go round, it's probably the least stressed part of the engine. But that's my call. I shall keep buying aftermarket ones. I don't change the tensioner either, unless it needs changing. I see that as another unnecessary precaution. Changing the tensioner every time you change the belt? You might as well change the water pump every time you change the alternator belts too then.
Problem is Roy that when you ask a question like that you will always get different responses. I have absolutely no evidence that aftermarket belts are inferior nor that tensioners are the cause of failures. I am not denying that it could, does, or might happen. But I don't have any evidence. Maybe someone who will advocate the genuine option will have some evidence.
I'd stick a Milner on one any day. At 170k there is the potential that if not already done previously, there could be wear showing in the tensioner. So it's worth considering for the money. When I did mine at 215K it was a good as new. So I left it. May have been done by someone else.
