A dodgy differential

Fiona - my cherished Volvo XC60 - has just done 97,000 miles.

That's quite a lot of mileage for six and a half years. And she hasn't been just a pretty thing on my front drive. She's had a definite job to do, quite a demanding one: to haul my caravan around the country for two months of the year. That's three tons of weight altogether - nearly two for Fiona, over a ton for the caravan.

In 2015 (the year in which I took the caravan as far north as Huntly in Aberdeenshire) Fiona towed the caravan nearly 3,300 miles. This year (2016) I have been more modest with my caravan holidays, but have still asked Fiona to do nearly 2,500 miles of towing. The coming year (2017) may not see more towing mileage than 2016, but I will certainly be back in Scotland. Very long trips are demanding on the tow car.

The ordinary, non-holiday mileage is significant too - it's about 10,000 to 11,000 miles annually. Quite a lot for a retired lady, but I live out of town and Fiona underpins all but my most local social life. She will always have to motor me around, because trains, and particularly buses, are inconvenient to use where I live.

Fiona has no lazy days. She never has had any.

Fiona is no ordinary, run-of-the-mill car. She is heavy with family associations. In January 2010, when I placed an order for Fiona to be built, she was the model at the very top of the XC60 diesel-engine range, with most of the extra options you could have on top of that. In fact the only big ones I did without were a built-in telephone, and Bluetooth, in order to keep within my budget. The budget was however generous. I had £34,000 of ring-fenced inheritance cash to spend, money that I'd promised Mum before she died that I would spend on a nice car and nothing else. It was money was from her late brother Des. The car would be a lasting memorial to him. Fiona's list price was £40,000, but Volvo gave me a standard allowance of £5,000 on my trade-in car, a deal I couldn't complain about because the traded-in car, a 1999 Honda CR-V, had cost me only £12,000 in 2002. The government's Scrappage Scheme, then coming to an end, shaved another £1,000 off the cash required, bringing it down to that magic £34,000. I managed to spend Uncle Des's inheritance almost to the penny.

Fiona was a very well researched and well-considered purchase. I looked at all the likely choices, both European and Far-Eastern. I wanted a large, tall, powerful, heavy, diesel-engined car with all-wheel automatic drive. It had to be strong on durability, safety features and driver aids. It had to be a very comfortable long-distance tourer, fully up to all my caravanning needs, but nice to drive about in when not hitched up. Even with £34,000 available, I couldn't quite step up to a new high-spec BMW or Mercedes. But there was still Audi, Volvo and Toyota. It came down to Volvo, on styling and Mum's Swedish ancestry.

Fiona is, by the way, the only new car I've ever owned in my life. And I was responsible for her birth. The gestation period was a long-seeming four months. But one day in May 2010 - it was 25th May 2010 actually, the first anniversary of Dad's death - I collected her from the Volvo dealer and she was mine. My baby. Getting a car built for you, to your individual specification, is not the same as choosing something 'suitable' or 'good enough' off the forecourt. It's so much more personal.

You can see from all this that - for me - Fiona has no ordinary significance as a car. So many associations are bound up in her. She reminds me of Mum, and Des, and even Dad - all of them now gone, just memories and faces in photos. She was also the first really major purchase in what I might call my new life, my post-M--- life. M--- actually sat in her for one short trip to South Wales in July 2010, a trip that did not go well. In fact it was emotionally awful. And Fiona and M--- did not get on. Fiona was not M---'s kind of car. She was my kind of car. And has since been my partner in many adventures that could never have included M---, quite apart from being a vital facilitator of the lifestyle that I have developed for myself.

I intended that Fiona would, with moderate care, last me fifteen years. Then I would feel content to give her an honourable retirement. That scenario is still realistic. And in 2016 she isn't even halfway through the original intended lifespan.

And now she has covered 97,000 miles, with 100,000 looming. That ought to be nothing too much for a Volvo, of course, but you can't cover so many miles without a certain amount of wear and tear. And a car that hauls a caravan will have somewhat more wear and tear than most. There has been a regular outlay on tyres and brakes, and other items that need periodic replacement. All of that was foreseen from the start, and it has cost. But I knew that Fiona would never be cheap to run. I also knew however that there would be benefits as well as costs. I have enjoyed those benefits very much.

Last year there was the first sign of mortality. She needed a major transplant. A new auto gearbox. I'd worn the old one out before its time. It cost £5,000. That was a lot of money. It was a shock. I did take a good long look at the alternatives, but concluded that I was better off paying that £5,000 and having a rejuvenated car.

This year, the second sign of mortality, elsewhere in the transmission. The source of the humming noise I first heard in 2015, which has lately become a worrying drone. The Volvo dealer has already had a preliminary look. The noise is coming from the rear differential, the mechanism at the rear of the car that distributes motive power to the rear wheels. I found a very clear video explanation by Toyota on YouTube of how simple differentials work - see https://www.youtube.com/watch?v=WeLm7wHvdxQ. Even I can understand how. I can also see that if any of those cogs get worn or damaged they might make the kind of noise I am now hearing. And that replacing these substantial mechanicals wouldn't be cheap. I am told that if this part of the differential is damaged, then I'd be looking at an all-in cost of around £2,750, much of it labour and VAT of course. Ouch.

But Fiona, being an all-wheel drive car, with all four wheels permanently powered, has a complicated differential that includes an electro-hydraulic device called a Haldex. YouTube has a video of the Mark 5 Haldex. Fiona's is Mark 4, but I should think it works on similar lines. The video is at https://www.youtube.com/watch?v=Tbs9TeS6Qxo. Looking at it, I can see why replacing a troublesome Haldex might easily cost a lot of money. I am told that if the Haldex is the culprit, then the all-in cost to me will be around £3,100. The labour charge is no different, but it's a slightly more expensive component. Ouch again.

But I said yes: go ahead, do your detailed examination, determine which bit is faulty, and replace it. I have put the money for this in place, enough to pay for the more expensive Haldex.

I am taking a long view. Two major transmission components will now have been replaced. I shouldn't need to worry about either during the rest of my ownership. They won't be looming as an Awful Possibility as I work my way towards 200,000 miles.

Mind you, that'll be £8,000 spent to maintain Fiona's transmission and keep her on the road. Some would say the economics don't stack up. But obviously there's more at stake here than how the sums work out. She is a cherished car, with important personal associations, and not a mere commodity. And her value to me as a cherished car trumps all other considerations - thus far, anyway.

In any case, I can't afford to change horses as the mood takes me. And if I could, or if it were vitally necessary to sell her and buy something else second-hand - as I did with the Honda back in 2002 - could I expect to end up with anything so comfortable and well-equipped? Probably not. Unless it were a Lexus, say. But tracking one of those down at short notice wouldn't be easy. And in any case, who knows what trouble I might be buying? Fiona is at least a known quantity.

So there you are. I'm putting on a brave face, shrugging my shoulders, and crossing my fingers, hoping that this is the last of any nasty surprises. I'm trying not to think of what else I might have done with that £8,000.