I'll prefix this by saying I will change the filter, but for the sake of debate...

So the service required message has come up, I'm not surprised, the missus has been using it day in day out for short trips, and I actually said to her yesterday that I thought it was needing an oil change as it sounds jingly ... ( hard to describe, but the tone of the engine chatter definitely changes as the oil dilution changes when it nears a service required ).

Its only been a few months / few k miles since the last oil change , and the thought struck me, given its only been a few thousand miles, and I'm swapping the oil out ... would the filter actually need changing ?

I cant really see that:


a) oil dilution would degrade the filter,
b) that the filter would hold any significant amount of diluted oil that would affect the new oil
c) Considering its meant to be run upto 16000miles, its well within its typical life

Anyone have any thoughts on it ?

I dont mind the change, it'll use up the last of my C1 oil. V8 or else ...

I'll play

What % of the total oil does the filter hold ? What constitutes a significant amount ? How much does a filter cost ?

I've not done a RR service myself, but I do my boat & the filter on that seems to hold around half a litre out of 5, so 10%. (Maybe it holds less and I'm mis-remembering )

I'll play back with very rough numbers:

The tdv8 is what I call a loo-roll filter and not the canister you screw on, so it doesn't hold a cup-full of oil like a canister would. By the time I've drained the oil out the engine, the filter will have drip drained a bit too ... so I reckon it'll may hold a quarter of a cola can ... so lets say maybe 100ml ? ( I think Its realistically less though ) The car seems to flag at needing a service when it thinks its around 7% dilution ... so old oil filter it may have 7ml of contaminant in it...

You typically refill just over 9 litres into the tdv8 ..

So the old oil in the filter would be about 1.1% of that 9 litres
and the contaminant about 0.07% of the 9 litres ... or 1% of total contaminant allowed.

Hmmmm.... I think at that sort of value, I'd be happy that if I didn't have a filter to hand and wanted to throw new oil in, I wouldn't be doing much harm in the grand scheme of things as the benefit of new oil far outweighs the harm of whats left in the filter. V8 or else ...

With those figures, I'd agree.

I'd think of the filter as more milage/usage based & not related to dilution issues requiring an earlier oil change.

As stated, I'm no mechanic though - or engineer for that matter

The filter won't release any oil just because the sump is drained but releasing the filter cap a few screw-turns will allow the oil to drain, but then don't forget to tighten it again later. However by not releasing the filter, oil can't drain from the bearings which whilst would drain a little more oil, would keep more oil in the galleries on start-up. Oil pressure takes longer to build after an oil change than on normal start-ups, as indicated by the rattle starting after an oil and filter change.

So in that case for this oil change it might be better not to change the filter? overfinch modified

New engine $25,000

Oil change $250

Oil filter $25

You do you… Dan. 🇨🇦 2013 L405 5.0 SCV8