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Swagman
X-TRAIL NEWBIE
Date Registered: 05-2009
Location: Victoria, Australia
TOTAL POSTS: 16
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Re: T31 M9R diesel oil
quote: dronus wrote:
I'm interested how the oil can play a part in fuel economy. I can see how it can affect the protection of the engine. Is it something to do with internal friction?
Ok, this is strictly "Oils101" stuff...I'm not an expert, so please jump in anyone if I say something that is not correct.
Oils are designed to separate metal from metal. Under load, thicker oils do this better than thinner oils, so its preferable to have a thicker oil than a thinner oil - all other things being equal. But the viscous drag of oils (that tends to prevent the "moving" part from moving freely) is higher for a thick oil than a thin oil. This means that assuming the lubrication ability is adequate, an oil that is thinner will be more slippery, and friction (and thus fuel consumption) will be reduced.
Next issue is temperature. Base oils have a tendency to become thinner with rise in temp (think of honey and what happens to it if you warm it). So as an oil gets warmer, its ability to keep the metal surfaces apart drops. Too thin, and the metal parts will still rub together.
Last issue is penetration. A thin oil will spread between the metal parts more easily than a thick oil.
Balancing these last two is where multigrades come in. When an engine is cold you need the oil to be thin so that it penetrates quickly and separates the metal surfaces as the engine starts. Once the engine is hot, you want the oil to be thick. This is achieved by adding substances that work the other way around - they become thicker with rise in temperature. So a 10W-30 oil acts as a 10 (thin oil) when the engine is cold and penetrates quickly between moving metal parts. When the oil warms up it acts like a 30 (thick oil) and provides better metal/metal separation.
There are other issues like "clingability" that refer to the ability of the oil NOT to drain out into the sump when you you stop the engine, but I won't go into them.
So the ideal oil would be a multigrade that had fast penetration, didn't thin with rising temp, and was super slippery so that it caused no drag (thus gave better economy). But such a beast isn't available and it's all a bit of a "swings and roundabouts" balancing issue.
Hope this helps.
Jeff.
(Edit: Oops - Sorry Kev...our posts "crossed in the mail")
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2008 T31 diesel TS manual, Twilight, tow pack, roof bars, left cargo drawer, all round protection mouldings, boot mat, floor mats
Last edited by Swagman, 27/Jul/2009, 2:05 pm
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27/Jul/2009, 2:02 pm
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Swagman
X-TRAIL NEWBIE
Date Registered: 05-2009
Location: Victoria, Australia
TOTAL POSTS: 16
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Re: T31 M9R diesel oil
Hi again,
I really should quit while I think I understand. There is a great discussion of HTHS in this thread.
But now my head hurts!
Jeff.
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2008 T31 diesel TS manual, Twilight, tow pack, roof bars, left cargo drawer, all round protection mouldings, boot mat, floor mats
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27/Jul/2009, 4:52 pm
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jalalski
Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29100
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Re: T31 M9R diesel oil
Here is some inside information for you guys
The genuine Nissan diesel oil is in fact Shell. When the diesel first came out here in Australia Shell didn't have the Nissan packaging ready in time, so dealers would use Shell oil packaging. This has now changed and the Shell oil is packaged in a Genuine Nissan packaging and probably sold for much more than Shell would sell it for.
Last edited by jalalski, 9/Aug/2009, 4:19 pm
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9/Aug/2009, 4:19 pm
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Swagman
X-TRAIL NEWBIE
Date Registered: 05-2009
Location: Victoria, Australia
TOTAL POSTS: 16
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Re: T31 M9R diesel oil
Hi Carts,
I, finally managed to source the Castrol Magnatec Professional C3 5W-40 at the local Castrol agent (Reliance). It's only available in a 20 litre container or 200 litre drum - I've been quoted $166 (20L) but they are out of stock Aus wide at the moment - expecting the next batch early September.
Castrol now have another C3 low SAPS oil Edge Sport 0W-40 - and this I've seen in 5L containers at the local Auto store that is Super Cheap. Note that there are OTHER Castrol Edge Sport oils of a suitable SAE grade for the M9R Exy (including a superseded 0W-40) that are NOT C3 compliant - so check the fine print on the side to make sure the one you pick up is definitely C3 rated.
Cheers,
Jeff.
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2008 T31 diesel TS manual, Twilight, tow pack, roof bars, left cargo drawer, all round protection mouldings, boot mat, floor mats
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14/Aug/2009, 9:31 pm
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