i've 2.4d xc60 and when bought- dealer had put in an unknown 10w40 due to its high mileage-113k.
when I had it serviced locally -garage put 0w30 in as correct spec from volvo -so I asked volvo-who said it should be 0w30 regardless of mileage as dpf might be affected-last service had put in a 'premium high quality synthetic oil,priced at half the 0w30 is to you and me.

there are 'high mileage' 10w40 premium synthetics advertised by major oil companies.

im on 144k now without issue and very good emission test results-im inclined to insist on the factory 0w30- any thoughts,as im definitely expecting to seek a high mileage out of the engine.

Hi

As it has a DPF, stick with the 0w-30 (or 5w-30) A5/B5.

High mileage oils don't really exist, it's more of a label thing they put on thicker grades as a decent oil will have seal swelling agents etc in them anyway.

Cheers

Tim

High mileage makes no difference whatsoever regarding engine wear , if you were to measure the bores and crankshaft bearings and seals they would be as good as new .
It is easy regarding grade ,the only oil for any mileage on this engine is 0w/30 A5/B5

I've recently stripped a 174k mile D5 engine I bought as it was the cheapest way of getting my hands on a replacement cylinder head for a project. The cylinder bores still had visible "criss cross" marks from the honing and no wear lip whatsoever. The big end bearings were indistinguishable from new.

as I said this is the norm for a volvo engine from my 47 years experience with the odd engine strip down .
I rebuilt a 1974 260 V6 once with 250000 miles on it , the bores and pistons and bearings were perfect all reused . just the head gaskets , liner heights , oil pump relief valve spring , camshafts and rockers , exhaust manifold studs needed attention ! so oil back in those days was just as good as the so called Improved oil of today .

Can anyone say if there is there any merit or not to using a 40 weight oil in a D5 - particularly if the car is regularly driven hard and is without DPF?

Some speculate that it would be bad for the turbo, whereas I am all too aware that people switch to a 40/50/60 weight oil in highly boosted Whiteblock engines to protect cylinder liners and other components with success.

The bigger risk around going to heavier oils is the effect on the hydraulic tappets - you are likely to reduce the valve clearances and that's not what you want.

The turbo bearings are probably the most primitive and less susceptible part of the engine, the priority here is an oil that does not break down or de-compose with heat. Whilst the RPM's are considerable, the forces are tiny.

A heavily boosted petrol T5 will be running at significantly higher RPM and cylinder temperatures than a D5.

So I'm doubtful there will be any benefit...

I doubt if anyone at all on here can tell you , It needs an oil chemist to do that and someone familiar with the engine ..
I know that on volvos oil chart from about 2004 said that do not use a /40 grade oil specifically.. volvo know best stick with that .

It really comes down to the oil temps. If the car is thrashed and modified, the oil is likely to run hotter, so the oil will be thinner and that would make a 5w-40 sensible (if the DPF has been removed). You can get around that (to an extent) with oil coolers, but it depends on the spec of the car.

Cheers

Tim

All the engines have quite an efficient oil to water heat exchanger which keeps the oil temperature pretty stable , I don't think anyone can possibly over heat the oil unless they are on a racing circuit , then a simple oil radiator would be usefull .