Yes its Ye Olde oil question again....

[xantiagreen]

Since owning the Xantia hdi 110 i've serviced it twice with total quartz 9000 5/40, 3rd service is 2 months away and I've been looking at the 9000 5/30 fuel economy, will there be any gains in fuel economy shifting over to 5/30 or very minimal (even if I get an extra 3-4 miles a gallon I'm ), will I need to flush the engine and use the 5/30 or just a good long drain is enough, both the 5/40 and 5/30 are the same price around £24.
Only do 3-4k a year all town driving and its currently close to 114k on clock.

Cheers

[Stickyfinger]

can't see it making any difference at all , with an engine that age I would stick to a 5/40 myself.

[Stewart(oily)]

Just changed mine for 5w40 after 10,000 miles and the engine does sound a little sweeter, I will not leave it as long next time. I think 8,000 is plenty.

[van ordinaire]

Changed mine as soon after I got it as was practicable because it was the colour - & consistency - of Indian ink. When I checked the level on re-filling the new oil looked the same, so intention was to do it again after 1,000 miles: that was about 1200 miles ago - but it always seems to be getting dark by the time I return from a run. Won't get much use now before the CCC National, so might have to just leave it ticking over for 5,10 mins. to warm it up. Then will revert to usual change every 3,000 (& probably the filter then too, rather than every 2nd oil change, as they're only about £2.50 a throw on line). I know oil technology's improved since that was the norm BUT (a) I won't pay those fancy prices & (b) any engine with a long, reliable life will almost certainly had oil/filter changes at those intervals.

[Peter.N.]

I change my Hdi's at 8000 miles, changed the XUD's at 5000 but the Hdi is cleaner burning. I use Trago Mill's best at about £13 for 5 litres, meets the spec for the 8 valve engines.

I have found from experience that the ambient temperature makes more difference to the fuel consumption than anything else, except the way you drive of course. My 406 averages just about 50mpg in the winter but at the moment is showing 55. It showed 64.8 when we returned from our Scotland trip a few weeks ago.

Peter

[van ordinaire]

Still think 8,000 miles is too long (& I don't care what the oil companies & car manufacturers say) BUT have to admit my 6,000 miles is more a target/objective than a religiously observed event.

Too bad I've used all the oil I bought in January on Trago's discount days (as oil was included in that promotional event this year!) - so back to Lidl's for their 15/40 @ about £10 for 5 litres when it's next available - interestingly their Irish stores do a corresponding semi-synthetic at the same price.

Still using Aucan's budget (5 litres for €8) stuff in the van - not up to spec but reasoning was, it was only being used as glorified flushing oil AND it still had to be better than what was in there when I bought it. Same hypermarket's own bran that IS up to spec is only €12-odd - so 5 litres x several will be coming back with me next time I'm near an Aucan in daylight.

Hoping to find 20, 25 litres of the difficult to get here 10/30 (or similar) at GDSF this year - for the Caddie!

As for fuel consumption being affected by temperature, I would've expected the opposite, simply because of the loss by evaporation BUT, then I've never even thought about it before, whereas you have some data.